FOREST INSECT AND DISEASE CONDITIONSBRITISH COLUMBIA AND YUKON - 1991

C.S. WoodG.A. Van Sickle

Forestry CanadaPacific and Yukon Region

Pacific Forestry CentreVictoria, B.C.

Information ReportBC-X-334

1992

Forestry CanadaPacific and Yukon RegionPacific Forestry Centre506 West Burnside RoadVictoria, British ColumbiaV8Z 1M5Phone (604) 363-0600

© Minister of Supply and Services Canada, 1992ISSN 0830-0453ISBN 0-662-19357-1Cat. No. Fo46-17/334EPrinted in Canada

Microfiches of this publication may be purchased from:

MicroMedia Inc.Place du Portage165, Hotel-de-VilleHull, QuebecJ3X 3X2

The National Library of Canada has catalogued this publication as follows:

Main entry under title:

Forest insect and disease conditions, British Columbia and Yukon

1979Annual[Information Report, ISSN 0830-0453;BC-X-334]Title from cover; title varies slightly.Volumes 1979-1984 issues as [Information report / Pacific Forest Research Centre : BC-X-Includes abstracts in French.ISSN 0837-6530

1. Trees — Diseases and pests — British Columbia. 2. Forest insects — British Columbia. 3. Trees— Diseases and pests — Yukon Territory. 4. Forest insects — Yukon Territory. I. Pacific ForestryCentre. II Pacific Forest Research Centre.

SB605.C32W66 1992 634.9'6'09711 C88-070584-1

CONTENTS

ABSTRACT/RESUME INTRODUCTION 1SUMMARY 2

PINE PESTS 4Mountain pine beetle 4Pinewood nematode 7Pine needle sheathminer 8A pine sawfly 8Pine needle diseases 8European pine shoot moth 9Scleroderris canker 9

DOUGLAS-FIR PESTS 9Western spruce budworm 9Douglas-fir tussock moth 11Douglas-fir beetle 14Western false hemlock looper 14

SPRUCE PESTS 15Spruce beetle 15Spruce aphid 17

TRUE FIR PESTS 17Budworms 17Western balsam bark beetle 18Fir engraver beetle 18A balsam shoot boring sawfly 18Balsam woolly adelgid 18

HEMLOCK PESTS 19Western blackheaded budworm 19Western hemlock looper 19Gray spruce looper 21

LARCH PESTS 21Larch casebearer 21Larch sawfly 21Green larch looper 22Larch needle diseases 22A larch shoot miner 22European larch canker 22

MULTIPLE HOST PESTS 22Black army cutworm 22Rhizina root disease 23Pests of young stands 23

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Seed orchard and nursery pests 25Root diseases 26Mammal damage 27Climatic injury 28Roadside conifer mortality 28Acid rain monitoring 28

DECIDUOUS AND ORNAMENTAL TREE PESTS 29Tent caterpillars 29Large aspen tortrix 30Gypsy moth 30Birch leaf miners 30Satin moth 30Western winter moth 31Winter moth and Bruce spanworm 31Jumping gall wasp 31An oak leaf phylloxeran 31Apple ermine moth 32Pear thrip 32Dogwood leaf blight 32

NEW RECORDS OF OCCURRENCE AND DISTRIBUTION 32

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AbstractThis summary of forest pest conditions in BritishColumbia and the Yukon Territory in 1991highlights pests that are or may become major forestmanagement problems. It was compiled from fieldreports and other records of eleven Forest Insect andDisease Survey rangers with contributions from theforest industry, researchers, and agencies. The statusand impact of more than 45 major forest pests aredescribed and some forecasts are made for 1992.

RésuméCe resume de l'etat des insectes et des maladies desarbres en Colombie-Britannique et au Yukon en1991 donne les grandes lignes de ce que sont oupourraient etre les grands problemes d'amenagementforestier. Il a ete compile a partir de rapports etautres releves effectues sur le terrain par les onzeforestiers du Releve des insectes et des maladies desarbres et des donnees fournies par l'industrieforestiere et des chercheurs et des organismesoeuvrant dans ce domaine. Il decrit l'etat et l'impactde plus de 45 insectes et maladies des arbresd'importance et presente certaines previsions pour1992.

Introduction

The Forest Insect and Disease Survey (FIDS) ofForestry Canada is responsible for producing anannual national overview of important forest pestconditions and their implications. In the Pacific andYukon Region, surveys to detect and monitorimportant forest insects and diseases andenvironmental factors are conducted. Additionally,surveys and records are maintained in support ofquarantine programs, forest research projects, andinsect collections and herbaria. Surveys areconducted with the cooperation of the BritishColumbia Forest Service, the forest industry, otherfederal and provincial agencies, municipalities,educational centers, and research programs at thePacific Forestry Centre and other Forestry Canadacentres across Canada.

This regional report reviews the status andimpact of major forest insects and diseases and theeffects of environmental factors on coniferous andbroadleaf forests in British Columbia and the YukonTerritory in 1991. Damage trends and expansion ofinfestations can be determined by comparison toprevious years' reports.

The subjective terms 'light', 'moderate', and`severe' are used throughout this report to describelevels of tree defoliation; these are defined as 1 to25%, 26 to 65%, and more than 65% defoliated,respectively.

The report is compiled from informationobtained largely from field observations and records

collected by 11 FIDS rangers during their fieldassignments from May to October in six provincialforest regions and the Yukon Territory. Moredetailed information on the status of forest pests isavailable in regional reports compiled by thefollowing rangers:

Cariboo - Bob Erickson and Bob FerrisKamloops - Peter Koot and Janice HodgeNelson - Leo Unger and Alan StewartPrince George - Nick Humphreys and Bob FerrisPrince Rupert - Rod Garbutt and

John VallentgoedVancouver - Rod Turnquist and Dennis ClarkeYukon Territory - Rod Garbutt

Other staff of the Forest Insect and DiseaseSurvey (FIDS) project in 1991 were:

Allan Van Sickle - FIDS HeadCohn Wood - Chief RangerJoan Strobbe - SecretaryLee Humble - Entomologist, insectary and

collectionBob Duncan - Biologist, insectary diagnosticsJane Seed - Technician, insectary rearing

and data baseBrenda Callan - Mycologist, diagnostics and

herbarium collectionDaphyne Lowe - Technician, herbarium

Summary

This summary is of pests that were most prominentin the Pacific and Yukon Region in 1991 and mostlikely to be of interest and concern to the forestcommunity. Equally significant in terms of lossesbut not reported in detail are several forest diseasessuch as root rots, stem rusts, cankers, decays, anddwarf mistletoes. These are perennial and, onceestablished, they fluctuate little from year to year, sothey are not surveyed on an annual basis.

The most noteworthy changes in the status ofmajor forest pests in 1991 included populationincreases of western spruce budworm, Douglas-firtussock moth, western hemlock looper, and grayspruce looper in the interior which resulted indefoliation of coniferous hosts over widespreadareas. The Asian biotype (race) of gypsy moth wasalso recorded for the first time in the region. Severeinfection of conifers and deciduous hosts by foliardiseases increased for the second consecutive year,particularly in the southern part of the province, dueto above-normal rainfall in the spring. Some forestinsect populations were delayed slightly but mostwere largely unaffected by climatic factors this year.

Mountain pine beetle was again the mostdamaging forest pest in British Columbia in 1991with an estimated 1.95 million m 3 of mature pinekilled in more than 9065 infestations which coveredabout 49 600 ha in six regions. Infestationsincreased overall, particularly in the KamloopsRegion, and are forecast to continue in 1992.Western pine beetle, red turpentine beetle,lodgepole pine beetle, and ambrosia beetle wereless common than in the three previous years, andpine engraver beetle populations remained at lowlevels for the fourth year. Pinewood nematoderemains very rare and is present only in a fewindividual predisposed trees at widely scatteredlocations. A cooperative study was initiated toinvestigate control of the nematode and its vector byheat treatment. Pine needle sheathminerpopulations again defoliated lodgepole pineregeneration in the southern interior, sometimes inassociation with western spruce budworm; however,sheathminer populations collapsed in southwestcoastal areas after five years of infestation.Populations of a pine sawfly in the Vancouver andPrince Rupert regions collapsed following up to twoconsecutive years of significant defoliation.Discoloration of year-old and older needles by pineneedle diseases was again common throughout the

interior, for the fifth consecutive year in some areas.European pine shoot moth remains established inornamental pines in urban areas in southwest coastalareas and the Okanagan Valley. The few shoots ofplantation Douglas-fir found infested for the firsttime in North America in 1989 and re-infested in1990 were treated and no further infested shootswere found. Scleroderris canker has been found onnative pines in British Columbia only at fourlocations prior to 1974, but has not been foundsince.

Douglas-fir and some lodgepole pine weredefoliated by western spruce budworm over morethan 395 000 ha in more than 800 separateinfestations in parts of three forest regions, morethan double the area infested in 1990. Most of theincrease was in the Kamloops Region. Increasednumbers of egg masses indicate that severedefoliation will occur in 1992 in most standsdefoliated in 1991. Patches of forest totaling 135 hain the Kamloops Region were defoliated for the firsttime since 1984 by increased numbers of Douglas-fir tussock moth; this pest also defoliated groups oftrees in the Vancouver Region for the second year.Ornamental trees in urban Kamloops and Okanagancommunities were defoliated for the fourthconsecutive year. Increased numbers of adults inpheromone traps and egg masses indicate thepotential for increased defoliation in both regions in1992. Mortality of mature Douglas-fir by Douglas-fir beetle increased for the fourth year to more than3160 groups of trees totaling about 3865 ha in partsof six forest regions, and is expected to continue in1992. Douglas-fir were defoliated by western falsehemlock looper in the Kamloops Region for the firsttime since the outbreak of 1981 to 1983. Thisfollowed two consecutive years of populationincreases. Populations are expected to continue toincrease in 1992.

The area and volume of mature and overmaturespruce killed by spruce beetle increased for thesecond consecutive year to more than 44 600 ha,mostly north of Mackenzie and north and east ofPrince George. This followed seven years of decline.Declining populations in recently windthrown andstanding spruce in Bowron Lakes Provincial Parkpose no immediate threat to healthy stands.Northern spruce engraver beetle killed tops ofmature and overmature spruce in parts of the PrinceGeorge Region. The area of alpine fir and white

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spruce defoliated in northeastern British Columbiaby eastern spruce budworm declined 40% to 245000 ha in 135 separate patches north and west of FortNelson where defoliation is forecast to continue in1992. Alpine fir and spruce forests in 61 areas over31 000 ha, mostly in the Prince George Region andto a lesser extent in the Kamloops and Nelson forestregions, were lightly defoliated by mature "off-cycle" 2-year-cycle budworms, up from 29 300 hain 1990. Immature "on-cycle" 2-year-cyclebudworm lightly defoliated new shoots of high-elevation fir and spruce in 40 areas over 5050 ha inthe eastern part of the Cariboo and Prince Georgeregions, and were present in high numbers in andnear Kootenay National Park in the Nelson Region.

More than 1200 pockets containing maturealpine fir recently killed by western balsam barkbeetle covered 62 500 ha in parts of six forestregions, mostly in the Prince Rupert Region.Mortality of grand fir by engraver beetles in thesouthern part of the Nelson Region declinedfollowing three years of outbreak. Balsam shootboring sawfly populations in true firs in parts of theNelson and Vancouver regions declined to theirendemic levels following significant shoot mortalityin some stands for up to three consecutive years.Active balsam woolly adelgid populations werefound on amabilis fir for the first time east ofLillooet Lake, slightly east of the existing quarantinezone in southwestern British Columbia, but damagewas not significant.

Western blackheaded budworm populationscollapsed in western hemlock near Holberg onnorthern Vancouver Island, down from a peak in1989 when stands over 7400 ha were defoliated.There was some recovery of immature trees top-killed during the outbreak. Old-growth westernhemlock was defoliated by western hemlock looperin 265 patches over more than 50 000 ha in threeforest regions, a major increase from eight patchesand 1115 ha in 1990. Generally severe defoliation isforcast in 1992, but it may be less severe in someareas due to larval parasitism and disease. Westernhemlock was lightly and moderately defoliated bygray spruce looper in 34 separate patches over 3850ha in the western part of the Nelson Region. Thiswas the second year of outbreak, mostly near Slocanand Upper Arrow lakes, and the first in the NelsonRegion. An entomopathogen killed up to 38% of thelarvae at two sites and could reduce populationsfurther in 1992.

Defoliation of western larch stands by larchcasebearer in southeastern British Columbia wasgenerally very light after high larval and pupal

parasitism in 1991. Larch sawfly populationsremained endemic in western larch in the EastKootenay, and continued to decline in tamarack innorthern British Columbia and the southwestern partof the Yukon Territory where very light defoliationoccurred in patches; populations also declined inexotic larch near Terrace, Prince George, Haney, andVancouver. Green larch looper populations inwestern larch at higher elevations in the WestKootenay collapsed following defoliation in 190patches over 12 000 ha in 1990, the first defoliationsince 1977. New infections and discoloration ofwestern larch by needle blights were widespreadand conspicuous throughout much of the host rangein the Nelson and Kamloops regions, as in 1990.

Black army cutworm populations generallyremained at low levels in recently burned andplanted sites in interior British Columbia in 1991, asthey did in the previous two years. Recently plantedseedlings were lightly defoliated by small numbersof larvae at only 4 of 44 sites in wetter parts of theNelson, Prince George, and Prince Rupert regions.High numbers of cutworm moths were caught inpheromone traps at eight sites and could pose athreat to seedlings in 1992. Fruiting bodies ofRhizina root disease, although generally lessnumerous and widespread than in 1990, killedrecently planted seedlings in seven sites in parts ofthe Nelson and Prince Rupert regions, down from 24sites in 1990.

Surveys of more than 250 young stands acrossthe province in 1991 found the most common, themost damaging, and the most widespread problemswere similar to those in 1990 and included theeffects of year-old climatic injury, animal feeding,and native needle diseases. Less common butlocally significant were root diseases, terminal androot collar weevils, and stem rust cankers.

The most common pests in coastal seed orchardsincluded Cooley spruce gall adelgid, which infestedDouglas-fir at five orchards and spruce at twoorchards; damage was mostly light but occasionallywas severe. Balsam wooly adelgid was common onamabilis fir at four seed orchards, balsam twigaphid deformed needles and twigs on true firs at twoorchards, and hemlock wooly adelgid lightlyinfested trees at one orchard.

In forest nurseries, increased severe infectionsby a leaf blight killed several thousand western redcedar seedlings at two sites in the VancouverRegion. However, seedling root rots were lesscommon, and a shoot blight found on hemlockseedlings for the first time in British Columbia wastreated.

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Mortality of up to 47% of the immature andmature conifers by root diseases includingArmillaria, blackstain, Inonotus, and Phellinus rootdiseases in more than a dozen sites surveyed in partsof at least three forest regions, resulted in significantvolume losses and created potential hazards in highuse recreational areas.

Feeding damage to conifers, including seedlings,by voles, porcupines, and squirrels occasionallyresulted in stocking reductions in parts of theKamloops, Nelson, Prince Rupert and Vancouverregions, and in the Yukon Territory. Recovery ofconifers from severe climatic injury in early 1989was generally good.

There was no evidence of damage or change inthe condition of trees and ground cover attributableto acid rain at 15 sample plots across the province.New mortality from other causes averaged 3% of thetrees.

Pests, particularly defoliators, were againnumerous and widespread in deciduous forests,particularly in stands of trembling aspen. Forest tentcaterpillar populations declined overall but stilldefoliated trees and shrubs at more than 320locations covering 113 000 ha near Prince George,near McBride, in the Peace River area, and to a lesserextent in the Cariboo and Kamloops regions.Northern tent caterpillar defoliated cottonwoodand other deciduous hosts over 4260 ha in the Skeenaand Wedeene river valleys in the western part of thePrince Rupert Region, in some areas for the thirdconsecutive year. Increased large aspen tortrixpopulations north of Mackenzie and along the AlaskaHighway defoliated aspen in about 45 areas totaling18 000 ha, double the area defoliated for the firsttime in 1990. Defoliation in southwestern YukonTerritory was widespread and less severe following

three consecutive years of infestation. About 72adult male gypsy moths were trapped in 17 areas inBritish Columbia in 1991 compared with 121 mothsin 16 areas in 1990. Some were the Asian biotype,the first record of this race in North America.Discoloration of native birch by leafminers remainedat low levels in parts of four forest regions.Following earlier declines, satin moth populationsremained low in the lower mainland, the northOkanagan Valley, and near Golden. Generallydeclining western winter moth populations lightlydefoliated maples and other deciduous hosts at onelocation in the Vancouver Region, but no damagewas noted elsewhere. Defoliation of deciduous hostsby winter moth was less severe in the lowermainland and on southern Vancouver Island,following a slight increase last year. Garry oakstands in the Greater Victoria area were severelydiscolored for the sixth consecutive year by highpopulations of the jumping gall wasp and to a lesserdegree by an introduced oak leaf phylloxeranDefoliation of apple and crabapple trees by anintroduced pest, apple ermine moth, was commonbut less widespread and less severe than in 1990 and1989 when its wide distribution in southern andsouthwestern British Columbia was first identified.Native and planted dogwoods in the southwesternpart of the Vancouver Region were again severelyinfected by dogwood leaf blight which killed lowerbranches and occasionally killed trees.

Six disease collections were new occurrencerecords within either British Columbia or the YukonTerritory in 1991, and an additional 14 diseases wererecorded for the first time on new hosts. Threeinsects were found beyond their previously knowndistributions, one was a new species, and one was afirst record for the insectary collection at Victoria.

Pine Pests

Mountain pine beetleDendroctonus ponderosae

The mountain pine beetle continues to be the mostdamaging forest insect in British Columbia. Thearea of lodgepole pine and some western white pinekilled by the beetle increased about 16% to morethan 49 600 ha in 9065 active infestations (Table 1)from the international border in the southeast tonortheast of Terrace (Map 1). This is nearly double

the area burned by forest fires in British Columbia in1991 (27 850 ha), and the volume lost (2 million m3)represents about 10% of the lodgepole pine annuallyharvested in British Columbia.

Active infestations continued throughout the sixforest regions in British Columbia, and are forecastto continue in 1992. The area of recently killedmature pine increased slightly overall, mostly in theKamloops Region, to 19 000 ha, up more thanthreefold from 1990. In the Nelson Region the areacontaining recently killed mature pine declined to

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Map 1. Areas where recent tree mortality due to mountain pine beetle was detected during aerial surveys in 1991.

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Table 1. Number, area and incidence of new and old attack of mountain pine beetle by forest region, based onrecently killed trees recorded by aerial and ground surveys in British Columbia in 1991.

ForestRegion

Number ofinfestations

Trees killeda Stands cruisedb

Avg. yrs.infested

Damage category

Area(ha)

No.(000)

Vol.(000 m3)

No. H C Rof trees

GP%

Cariboo 294 350 17 5 2 2 49 11 31 9 0Kamloops 2685 19 000 3520 1368 5 5 73 10 12 4 1Nelson 4293 14 675 763 275 22 5 51 18 21 6 4Prince Georged 306 9300 334 267 2 5 65 7 11 12 5Prince Rupertd 1417 5850 136 81 1 4 45 0 16 30 9Vancouver 71 465 7 6

Total 9066 49 640 4777 2002 32 5 57 9 18 12 4

a Trees attacked in 1990, discolored in 1991.

b Some stands located in younger infestations may not represent average condition.

c H - Healthy; C - Current, attacked in 1991; R - Red, attacked in 1990; G - Grey, attacked in or before 1989;

P - Partial or strip attacked in 1991.

d Estimates include data from the B. C. Forest Service

14 675 ha, down 35%. In other regions, areas ofrecently killed mature pine were mapped over 350 hain the Cariboo Region (up 15% from 1990), 9300 hain the Prince George Region (up 14%), 5300 ha inthe Prince Rupert Region (up 30%), and 465 ha inthe Vancouver Region (down 14%).

In the Cariboo Region, infestations increasedoverall to 350 ha from 300 ha in 1990, but declinedslightly at Chilko Lake. Recent pine mortality andnew attacks increased slightly in mixed coniferstands in the eastern part of the region and areexpected to continue to increase in 1992. Pinemortality near Chilko Lake is expected to decline atthe west end of Franklyn Arm due to reduced hostavailability, but susceptible pine to the north and eastof the lake are vulnerable to attack.

The area of mature pine killed by the beetle inthe Kamloops Region in 1991 increased threefold,following three years of decline, to 19 000 ha.About 3.5 million mature pine (1 368 000 m3 ) werekilled in about 2685 pockets, mostly over 16 450 hain the Okanagan Timber Supply Area (TSA). In theMerritt TSA there were 475 pockets of pinemortality totaling 880 ha. Groups of 5 to 10 beetle-killed white pine were again numerous near Adams

and Barriere lakes and from Vavenby to Albreda inthe Kamloops TSA. Tree mortality is forecast tocontinue in the Kamloops Region in 1992, mostly inthe Okanagan and Merritt TSAs where current attackin five stands averaged 10% (range 3%-24%), down6% from 1990.

Infestations in the Nelson Region declined to 14675 ha in about 4290 separate pockets containing anestimated 763 000 attacked trees (275 000 m3 ). Thedeclines were mostly in the southern half of theBoundary TSA in the West Kootenay where treemortality had been increasing for the previous fouryears. Elsewhere, there was a significant increase inthe southern part of the Cranbrook TSA, but littlechange in the Invermere, Arrow, Kootenay, andRevelstoke TSAs. Infestations along the BritishColumbia-Alberta border and in Glacier and Yohonational parks were generally stable for the fifthyear, but increased threefold in Kootenay NationalPark. Small groups of recently killed pine werecommon in the Flathead and Elk river valleys,following an increase in 1989. An average of 18%of the trees were attacked in 1991 in 22 standssurveyed in the region; this is a decline of 8% from1990 but indicates continuing tree mortality in 1992.

Current attacks were again highest in the EastKootenay (average 24%, range 2-52%); damagedareas included Bull River, Moyie Lake, near Parsons,Golden, and in Kootenay and Glacier national parks.New attacks in the West Kootenay declined overall(average 10%, range 2-19%) in eight stands infestedon average for 5 years; the highest levels of attackoccurred at West Boundary Creek and in the upperRock Creek drainage in the Boundary TSA.

The area containing recently killed pine in thePrince George Region increased about 15% to 9300ha, following an increase to 8000 ha from 1989 to1990. Most of the 305 separate infestations, whichcontained about 334 000 trees (267 000 m 3 ), againwere in drainages northwest of Fort St. James, andincluded areas near Takla and Trembleur lakeswhere most of the increases occurred, and someareas in the Skeena, Sustut, Middle, and Tachie rivervalleys. Pine mortality is forecast to continue in theregion in 1992, but tree mortality will decline in theFort St. James area. New attacks in two stands in thearea averaged 7%.

Aerial and ground surveys by the BritishColumbia Forest Service in Mt. Robson ProvincialPark and west of Jasper National Park located nonew beetle-killed pine, but 104 baited pine werenewly attacked. Annual cut-and-burn controloperations, which have been conducted since 1985,are scheduled to treat these trees in 1991-92.

Infestations in the Prince Rupert Regionincreased about 40% in area to 5850 ha andcontained about 136 300 trees (81 160 m3 ) in 1417separate infestations. The increase, following adecline in 1990 in the western part and to a lesserextent in the eastern part of the region, was in thelower Nass River Valley in the Kalum TSA and partsof the Bulkley and Morice TSAs. Tree mortality isforecast to decline in 1992; this prediction is basedon the low proportion (less than 1%) of the treesattacked in 1991 in a stand infested for about 4 years.

The number and area of mature lodgepole pinekilled by mountain pine beetle in the VancouverRegion declined to the lowest level recorded in theregion since 1981 when infestations were firstmapped in the Homathko River Valley and east ofPemberton. About 7000 trees (5000 m 3 ) wererecently killed in about 70 separate pockets totaling465 ha, down from 540 ha, in widely scattered partsof the Soo TSA mostly east of Pemberton. Based onthe trend of declining host availability over the past 6years, pine mortality is expected to decline further.Surveys of the declining and remote infestationswere discontinued in 1990.

Overwintering mortality of the mountain pine

beetle was common, particularly in thinner barkedtrees in the southern interior in early March. A ratioof progeny to parents in May-June greater than 4.1indicates increasing populations; such ratiosoccurred at only 16 of 54 locations, and they werereflected in reduced current/green attacks. Ratios ofless than 2.5 indicate declining populations and theseoccurred at 29 locations. The average regionalvalues ranged from 2.2 to 3.9, down from 4.3 to 13.1in 1990; this indicated declining populations forflight and attack during 1991.

Overall, infestations are forecast to continue in1992 throughout many recently infested pine standsin parts of five forest regions. This prediction isbased on the number of new attacks in 31representative stands infested on average for 5 years.Current attacks declined from 1990 levels in fourregions. The frequency of new attacks in all regionsaveraged 9%, down 9% from 1990, and ranged from18% in the Nelson Region to 0% in the western partof the Prince Rupert Region.

Increased numbers of western white pine werealso killed by mountain pine beetle in the northernpart of the Kamloops Region for the secondconsecutive year. Other bark beetles such as westernpine beetle, Dendroctonus brevicomis, and redturpentine beetle, D. valens, were less common thanin 1990 in parts of the Kamloops and Nelson regions,respectively. Pine engraver beetle, Ips pini, whichhad been common in mountain pine beetleinfestations in the interior regions during 1966-1988also remained at low levels. Attacks by ambrosiabeetles, Trypodendron spp., were less widespread instands infested by mountain pine beetle in parts ofthe Cariboo, Nelson, and Prince George regions.

Single-tree disposal and salvage of beetle-killedand adjacent susceptible pine continued at highlevels in most beetle-infested TSAs. Salvageharvesting of economically accessible beetle-killedpine may be affected by high inventories in adeclining market. There were no reports yet ofreduced annual allowable cuts as a result of earlierincreased salvage harvesting, but this is likely tohappen soon.

Pinewood nematodeBursaphelenchus xylophilus

The nematode remains extremely rare in forests inBritish Columbia and the Yukon Territory. About2000 samples have been examined from recentlydead or dying trees, logs, low grade boards, andpotential vectors collected throughout BritishColumbia. Only a few individual predisposed trees

have been affected at widely scattered locations.Only six of those samples (0.3% incidence)examined in the region since 1980 containedpinewood nematode. There was none in 319extractions from western hemlock and western redcedar. A single Monochamus woodborer has beendetected in only one of about 575 hemlock logs butnone has been found in cedar examined in 16 coastallog storage yards in 1990.

Prior to the ban on exports of non-kiln-driedsoftwood from Canada imposed by the EuropeanEconomic Community, which recently has beengranted a further 1 year deferral, a cooperative studywas initiated to investigate control of the nematodeand its potential vector, Monochamus spp. by heattreatment. In cooperation with the Council of ForestIndustries (COFI) and Forintek, a total of 31 dry landsorts and areas of felled and bucked material wereexamined throughout the region by FIDS in 1991.Only nine sites contained small numbers of affectedlogs. Twenty-four logs were selected from a sitenear Squamish. Insects present in a representativesample included the whitespotted sawyer beetle,Monochamus scutellatus, a cerambycid woodborer,Leptura sp., darkling beetles, Ipthimus serratus andPhellopsis porcata, and a carabid predator,Scaphinotus nagusticollis. Results of the heatpasteurization trial are pending.

Pine needle sheathminerZelleria haimbachi

Defoliation and needle mining of lodgepole pine bysheathminer in the Kamloops Region declinedoverall by more than half to 11 700 ha in 52 separateareas. However, pine were defoliated by thesheathminer in association with western sprucebudworm, Choristoneura occidentalis, in anadditional 12 infestations totaling 13 500 ha.Populations in the Vancouver Region collapsedfollowing five years of discoloration, andpopulations remained low near Grand Forks in theNelson Region after their collapse in 1990.

Discoloration of immature lodgepole pineregeneration in the Kamloops Region was light over5875 ha and moderate over 5075 ha; the level ofdamage was similar to that recorded in 1990. Severediscoloration was in association with western sprucebudworm and was limited to three areas totaling 650ha south of Salmon Arm near Shuswap Lake and toimmature pine in a 30-ha plantation at Bear Creeknortheast of Kelowna. This was only the secondrecord of damage in the Okanagan since aninfestation in the early 1950s. Most discoloration

was in 29 areas from Seymour Arm to the north endof Adams Lake, and near Clearwater and Avola inthe North Thompson River drainage. The decliningpopulations were mostly near Barriere lakes andadjacent parts of Adams Lake.

Populations of the sheathminer in pine stands inthe Vancouver Region near Pemberton, D'Arcy,Harrison Lake, near Boston Bar, and on TexadaIsland collapsed after being active in some areas forfive consecutive years. Although incrementreduction may have occurred following larval miningand defoliation for up to five consecutive years, therewas no apparent reduction of lateral or heightgrowth, and infested stands are expected to recover.Overwintering population assessments wereinsufficient to forecast trends in 1992.

A pine sawflyNeodiprion nanulus contortae

Sawfly populations in the Vancouver Regioncollapsed following two consecutive years of severedefoliation of lodgepole pine in widespread locationsat higher elevations in the lower mainland.Populations in the eastern part of the Prince RupertRegion also declined.

There was no evidence of larval feeding in aplantation at Spuzzum Creek, near Yale, where 15-to 20-year-old lodgepole pine over 15 ha had beenseverely defoliated in previous years. Previouslydefoliated pine in urban areas near Mission showedsigns of recovery after having lost up to 90% of theolder needles.

Pine needle diseasesElytroderma deformansLophodermella concolor

Lophodermella montivagaScirrhia pini

Infection of year-old needles of lodgepole andponderosa pines by native needle diseases was againcommon in the Cariboo, Kamloops, and Nelsonregions, and was present to a lesser extent in theVancouver Region.

Infection of year-old and older lodgepole pineneedles by Lophodermella needle diseases wassevere and widespread in the Kamloops and Nelsonregions. In the North Thompson River drainage inthe Kamloops Region, infection was severe for thesecond consecutive year. Up to 50% of the year-oldneedles on up to 80% of the regeneration and maturelodgepole pine were discolored in patches in the

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Lillooet TSA, including areas in the Marshall andHurley creek valleys, at Miledge Creek north of BlueRiver, and again throughout the Okanagan Valleydrainages.

In the Nelson Forest Region, patches oflodgepole pine totaling up to 5800 ha were severelydiscolored in the Bull River Valley and in theFlathead River and Lodgepole Creek drainages.Discoloration was widespread in 25- to 35-year-oldstands over 300 ha in the Spillimacheen and Whiteriver valleys; damage was generally light althoughmoderate levels of discoloration occurred in someareas. Infection of western white pine was light andoccasionally moderate in the western part of theregion.

Up to 60% of the year-old needles, mostly in thelower crowns of immature lodgepole pine, wereinfected by red band needle disease, S. pini, inpatches up to 5 ha west of Lac La Hache in theCariboo Region. Infection of the mid-crowns ofmost regeneration white pine was common fromAlbreda to Avola in the Kamloops Region.Successive years of severe infection in immaturelodgepole pine stands result in premature needle lossand increment reduction.

Infection of ponderosa pine by Elytrodermaneedle disease is widespread throughout much of thehost range in the Cariboo and Kamloops regions andis present to a lesser extent in the Nelson Region.Severe annual infections have resulted in prematureneedle loss on most trees over widespread areas.Nearly half the crowns on mature and immature treeswere infected and discolored from 100 Mile Houseto Chasm in the Cariboo Region, and up to 80% ofthe year-old needles were discolored and 80% of thetrees were broomed in stands near Kamloops Lake.

European pine shoot mothRhyacionia buoliana

The shoot moth is established in exotic pines inlocalized urban areas including the OkanaganValley, the lower mainland, and from Victoria toCourtenay. There has been no evidence of shootmoth populations in native pines.

An average of 30% (range 20-40%) of the newshoots of exotic pines at two urban sites in Penticton,where infested and distorted shoots have occurredannually for many years despite periodic treatments,were again infested.

Surveys in 1989 detected the shoot moth onDouglas-fir, which is the first record on this host inNorth America. Only two Douglas-fir shoots in amixed conifer Christmas tree plantation at Richmondin the Vancouver Region were infested and threemore were found in 1990. These infestations wereprobably due to the immediate proximity ofnumerous severely infested Scots pine. No Douglas-fir were infested in 1991 following treatment of theinfested trees.

Scleroderris cankerGremmeniella abietina

A North American strain of this fungus, but not theintroduced pathogen, has been found only rarely as alower branch saprophyte near Penticton, Canal Flats,Castlegar, and Kimberley between 1968 and 1978during surveys of native lodgepole, ponderosa, andwhitebark pine in British Columbia.

Formal surveys for the introduced Scleroderriscanker were all negative and were discontinued in1988.

Douglas-fir Pests

Western spruce budwormChoristoneura occidentalis

Mixed-age interior Douglas-fir in parts of threeforest regions were defoliated by western sprucebudworm over 382 000 ha in 1991 (Map 2); this isnearly double the area affected in 1990 but less thanthe peak of 800 000 ha in 1987. In addition,lodgepole pine over 13 500 ha in the KamloopsRegion were defoliated by the western sprucebudworm, in association with a pine needle

sheathminer, Zellaria haimbachii. There were nearly800 separate areas of infestation in Douglas-firforests of which 97% (372 000 ha) were in theKamloops Region, 1% in the Nelson Region, and 2%in the Vancouver Region. Trace defoliation wasdetected over about 10 ha west of Clinton in theCariboo Region, the first in the area since 1986.

Defoliation also intensified in 1991; lightdefoliation occurred on 28% of the area, moderate on59%, and severe on 13%, compared with 46%, 52%,and 2%, respectively, in 1990. The most severe

9

Map 2. Defoliation by western spruce budworm detected by aerial surveys in 1991.

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0 100 200 km

1

defoliation occurred on 49 500 ha in 100 patches westof Lillooet, near Lytton, Ashcroft, Merritt, Kamloops,Shuswap Lake, Vernon, Kelowna, and Penticton.

Areas of expanded defoliation totaled about 200000 ha. These included the Okanagan TSA includingthe Shuswap, (where defoliation increased 36% to240 500 ha) the Kamloops TSA (up eightfold tonearly 70 000 ha), the Lillooet TSA (up threefold to78 250), and the Merritt TSA (up more thansevenfold to 1800 ha). Areas of infestationsincreased about fourfold in the Boundary TSA in theNelson Region, and by 50% near Pemberton in theVancouver Region.

Of the total area infested since 1985, 49% hasbeen defoliated for 1 year, 36% for 2 years, 9% for 3years, and 1-3% for each of 4, 5, and 6 years.

Parasitism of late-instar larvae occurred at 16 of18 sites sampled in two regions, and averaged 6%(range 0-21%); as in 1991, parasitism was mostly bytachinids, ichneumonids and braconids. Anentomopathogen, Beauvaria sp., was isolated fromlarvae in 14 collections in which an average of 38%(range 1-85%) were killed. The presence ofBeauvaria in populations in the Nelson Regionreduced the extent and severity of defoliation fromthat forecast; an average of 45% of the buds wereinfested in spring 1991, up from 25% in 1990.

Still, 20% more egg masses than in 1990 werecollected at 63 infested stands in three regions,indicating an overall increase(Map 3). Defoliation isforecast to be severe at 42 of the sites, mostly in theKamloops and Nelson regions. Moderate defoliationis forecast at 16 sites and light defoliation at 5 sites.Additionally, egg sampling by the British ColumbiaForest Service at 201 sites in three districts in theKamloops Region indicated severe defoliation at10% of the sites mostly in the Vernon District,moderate defoliation at 27% of the sites, lightdefoliation at 54%, and none at 9% of the sites,mostly in the Salmon Arm District.

Tree mortality, top-kill, bud mortality,increment loss, and tree deformity due to successiveyears of severe defoliation are common but vary bysite. Monitoring of the impacts of defoliation onyoung open-growing Douglas-fir continued at 64research plots in the Kamloops Region. Treemortality in 1991 averaged 10% (range 3-12%). Atrend of increasing tree mortality with increasingyears of defoliation has been determined (R. Alfaro,Forestry Canada, Victoria, personal communication).

Aerial applications of Bacillus thuringiensis var.kurstaki by the British Columbia Forest Service wereconducted over about 3000 ha near Westwold andPillar Lake in the Kamloops Region in 1991.

As part of a study to improve and calibratedetection methods for western spruce budworm,mid- to late-instar budworm larvae and adult maleswere monitored in four regions at 11 sites with ahistory of budworm outbreaks but still with lowpopulations. Up to 99 larvae per tree were collectedper 1 m 2 beating (three branches on each of 25trees/plot) and up to 605 male adults were caught ina total of 54 traps. Further analysis and sampling areplanned to correlate numbers of larvae withpopulation potential and damage.

Douglas-fir tussock mothOrgyia pseudotsugata

Douglas-fir trees were severely defoliated in eightareas totaling 135 ha west of Kamloops, and smallgroups of hedgerow and ornamental Douglas-fir nearAbbotsford, Chilliwack, and Clearbrook in theVancouver Region were defoliated for a secondconsecutive year. This followed population increasesdetected in standard three-tree beating samples innatural stands in the Okanagan and Thompson valleysin 1989 and 1990, and for the first time since 1983 inthe Fraser Valley. Ornamental Douglas-fir andspruce in urban areas in Kamloops, Vernon,Kelowna, and Penticton were defoliated, some for thefourth consecutive year. However, populationswhich had increased in 1990 and early 1991 nearHedley and Keremeos declined due to viral infection.

The number of male adults in pheromone-baitedsticky traps placed in selected Douglas-fir stands withthe greatest historical frequency of outbreaksincreased for the sixth consecutive year. About 3807adult males were trapped in 92% of the traps at 17permanent monitoring sites in the Kamloops Region.This is 70% more than the number trapped in 1990and more than double the number trapped in 1989.The number of male adults trapped in the westernpart of the Nelson Region also increased to 443caught in 12 traps at two locations, compared to 156adults in 1990.

Additional traps were placed singly about 1 kmapart in five areas in the Kamloops Region to moreprecisely locate any infestation. These attracted 3262male adults in 54 of 55 traps, up from 2233 in 1990and 1782 in 1989. A further 6176 male adults weretrapped at 186 locations monitored by the BritishColumbia Forest Service, up from 1616 at 80locations in 1990.

Trap data and the presence of egg masses ordefoliation in 1991 at 32 of 37 sites (Map 4) indicatethe potential for severe defoliation of Douglas-fir ateight sites, moderate defoliation at six sites, and light

11

® NONE Qi MODERATE

0 LIGHT • SEVERE

BLUE RIVER

CLEARWATER

SHUSWAP LAKE

0 40 80 km

I I IFORESTRY CANADA / FOREST INSECT AND DISEASE SURVEY

Map 3. Defoliation by western spruce budworm forecast for 1992, based on 1991 egg surveys.

12

I 1 I

0 NONE ■■■■ MODERATE

0 LIGHT • SEVERE

IndianGardens

SHUSWAP LAKE

lkPENTICTON

ilII '4 AL

Similkameen

FORESTRY CANADA / FOREST INSECT AND DISEASE SURVEY

Map 4. Defoliation by Douglas-fir tussock moth forecast for 1992, based on 1991 egg surveys.

or trace defoliation at 18 sites. Defoliation may occurin patches from Keremeos to north and west ofKamloops, near Chilliwack, and to a lesser degree inthe western part of the Nelson Region.

Treatments of populations over 200 ha nearSavona with two virus types (Virtuss and TM-Biocontrol-1) and an experimental pheromone maleconfusion trial near Hedley were completedfollowing delays in population development. Postspray results from Savona indicated a significantpopulation reduction. Preliminary results fromHedley indicated mating was effectively blocked.

Douglas-fir beetleDendroctonus pseudotsugae

Nearly 3000 groups of recently killed Douglas-fir totaled about 3800 ha, up from 2700 ha in 1990.Most of the recently killed trees were in groups of 2to 15, but some patches contained up to 250 deadtrees. Most of the tree mortality occurred in theFraser River drainage in the Cariboo, Kamloops,Prince George and Vancouver regions, althoughlesser damage occurred in the Nelson Region and inthe eastern part of the Prince Rupert Region. Thiswas the fourth consecutive year in which the numberof Douglas-fir killed by the beetle increased. Manyof the trees were predisposed by root disease.

Most of the estimated 33 000 (71 200 m3)recently killed trees in the Cariboo Region wereagain widely scattered in 2030 separate pocketstotaling about 1785 ha, down slightly from 1990.Most were in or near previously infested patchesfrom Clinton north to Quesnel and from Horseflywest to Redstone. The area containing recentlykilled trees in the military training area near RiskeCreek increased slightly to 216 patches totaling390 ha, up from 176 patches totaling 370 ha in 1990.In the Kamloops Region more than 700 groups werewidely scattered in the Thompson River drainageover a total of 235 ha, a threefold increase. Mostgroups of beetle-killed trees occurred from CacheCreek to Pavilion, in the Deadman River Valley, andthere were a few patches between Barriere andClearwater. Mature beetle-killed Douglas-fir wereless numerous throughout the Rocky MountainTrench in the Nelson Region in scattered groupsfrom south of Radium to the international border.

Smaller groups were less common in the WestKootenay. Douglas-fir mortality in 200 patches westof Prince George and south of Valemount increasedto 1545 ha, up from 800 ha in 1990. A patch ofabout 300 trees at the east end of Francois Lake inthe Prince Rupert Region killed in 1990 (the firstmortality from the beetle in the area in recent years)was harvested and no additional tree mortality wasrecorded. In the Vancouver Region, beetle-killedtrees were mapped in 57 areas over 235 ha, which issimilar to the damage recorded in 1990. Thisincluded 13 patches in the Anderson River drainageand more than 40 patches totaling 140 ha nearLillooet Lake.

The number of new attacks in trees adjacent torecently killed trees indicates that mortality ofmature and overmature Douglas-fir will likelycontinue in 1992, particularly in the Cariboo Region.In the military training area near Riske Creek, 17%of the trees are currently attacked, up 6% from 1990.Elsewhere in the region 3% were attacked down 11%from 1990. Tree mortality is forecast to continue instands predisposed by fire and root disease north ofGolden but a decline is forecast from Invermeresouth to Cranbrook.

Western false hemlock looperNepytia freemani

Defoliation of Douglas-fir by western false hemlocklooper occurred in the Kamloops Region for the firsttime since 1977 over about 10 ha at Jamieson Creeknorth of Kamloops. This followed three consecutiveyears of population increases.

About 110 larvae, up from 33 in 1990 and 20 in1989, were collected in standard FIDS samples atpermanent sample sites from Savona to Chase,Kamloops to Barriere, Penticton, the SimilkameenRiver Valley, and near Spences Bridge. However,the low numbers of larvae and the few eggs onneedles of Douglas-fir indicate that populations arestill too low to cause visible defoliation in 1992.Periodic infestations have occurred in parts of theKamloops Region. The most recent infestation wasin 1983-84. These infestations are usually concurrentwith infestations of Douglas-fir tussock moth,0. pseudotsugae, which increased and defoliatednatural stands elsewhere in the region this year.

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Spruce Pests

Spruce beetleDendroctonus rufipennis

The area and volume of mature white andEngelmann spruce killed by this beetle in BritishColumbia increased for the second consecutive year;this followed seven years of decline. Most of theinfested spruce mapped in aerial surveys was in thePrince George Region and totalled over 44 600 ha,up from 13 150 ha in 1990. The major increase wasin standing mature spruce north of Mackenzie and toa lesser extent north and east of Prince George nearCarp and Weedon lakes, and in the Parsnip andMcGregor river drainages (Map 5).

Tree mortality in the Prince George Regionincreased for the second consecutive year. Beetle-killed mature spruce were mapped in more than1210 widely scattered patches totaling 44 400 ha.According to data largely provided by the BritishColumbia Forest Service, the increase in mortalitywas in standing spruce in mixed species and ageclasses over 32 400 ha west of Williston Lake in theMackenzie TSA. Increased mortality over 10630 ha also occurred in the Prince George TSA inthe Summit, Davie, Carp, and McLeod lakes area,at Seebach and Averil creeks, and the upper Parsnipand McGregor river drainages. Mortality ofstanding trees occurred in four patches totaling 200ha north of Fort St. James, and east of Fort Nelson,but elsewhere in the region populations generallydeclined to endemic levels. Only a few new attacksoccurred in windthrow, trap trees and somestanding trees between Pine Pass and Chetwynd,south of Dawson Creek, and southwest of Hudson'sHope.

Spruce beetle populations found in 20 of 28areas examined in cooperative inter-agency surveysof beetle-infested spruce stands north of Mackenziein the Prince George Region may be a potentialthreat to adjacent healthy spruce when populationsmature in 1993. Evidence of attack since 1985 waspresent in or adjacent to most stands and, except fora small flight in 1990, most populations were in the2-year cycle which peaked in 1989. New (1991)attacks were common in trees previously attacked in1989 or 1990; these were mostly light, althoughsome attacks were severe. Most of the recent treemortality occurred in the Chunamen Creek drainagewest of Williston Lake, where new attacks were

found in an average of 35% (range 0-75%) of thegreen standing spruce in mixed species and ageclasses at 16 sites. New attacks at 10 sites in thePhillips, Mischinsinlika, and Trappers creekdrainages averaged 16% (range 1-53%), but no newattacks were found at an additional two sites.

Proposed stand treatments prior to broodemergence in 1993 include harvesting and lethal andnon-lethal trap trees; these treatments and additionalprobes and long-term monitoring could limit thethreat to adjacent non-infested stands.

There was no increase in the infestation inBowron Lake Provincial Park which was largelyconfined to mature and overmature sprucewindthrown in 1990 in 65 patches totaling 700 ha.Follow-up surveys in cooperation with the BritishColumbia Forest Service and British ColumbiaMinistry of Parks in 15 representative patches ofblowdown on the west arm of Isaac Lake and facingWolverine Bay found less than five new attacks persite in single widely scattered 1991 windthrownspruce, too few to be a potential hazard in 1992-93.Patches of windthrown spruce attacked in 1990contained an average of 12 attacks per square metreof bark area. Most (80%) broods were 2-year-cycle,which are forecast to emerge and attack susceptiblehost material next year. Elsewhere in the region,recent tree mortality totaled about 65 ha in 64widespread pockets near Barkerville, in the Mitchell,Matthew, and Cariboo river drainages, and nearTowkuh, Big Valley, Rebman, and Alice creeks; asimilar level of mortality occurred in 1990.

Recent mortality of mature spruce in theKamloops Region was generally confined topreviously infested stands in seven separate patchestotaling 335 ha, down from 17 patches over 1000 hain 1990. Declines, mostly due to harvesting and hostdepletion, occurred in the Tulameen River drainagewest of Princeton, between Anderson and Bridgelakes west of Lillooet, and near the south end ofAdams Lake.

In the Nelson Region, populations generallywere at endemic levels for the third year. Recenttree mortality occurred only over 20 ha at EnsignCreek in the Blaeberry River drainage north ofGolden where a third of the mature spruce adjacentto recently logged areas were attacked. Smallnumbers of mature spruce in the upper FlatheadRiver drainage have died from the combined effects

15

2

Te

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0 100 200 km

Map 5. Areas where tree mortality and defoliation was detected by aerial surveys in 1991.

1. Spruce beetle2. Eastern spruce budworm3. Forest tent caterpillar4. 2-year-cycle spruce budworm5. Western hemlock looper6. Gray spruce looper

of climatic injury in early 1989 and beetle attacks in1990.

Populations of northern spruce engraver beetle,Ips perturbatus, increased slightly in parts of thePrince George Region in 1991. The top third of thecrowns of mature and overmature spruce were killedat widely scattered locations in the Torpy Riverdrainage and west of Takla Lake north of Fort St.James. This followed slight population increases inspruce windthrow and trap trees in 1990.

Spruce aphidElatobium abietinum

Populations of spruce aphid in coastal areas of theVancouver Region, particularly at Campbell River,defoliated immature and mature Sitka andornamental spruce for the second year, and

populations increased significantly on the QueenCharlotte Islands.

Defoliation was generally less severe than in1990; however, some mature Sitka spruce in theCampbell River area that were severely defoliated in1990 and 1991 are not expected to recover.Elsewhere, populations declined from Powell Riverto Langdale, on Texada Island, and east to Hope.

Increased spruce aphid populations on theQueen Charlotte Islands severely defoliated coastalspruce regeneration in the Lawn Hill area and a 100-ha plantation near Heather Lake. Light andmoderately defoliated spruce were commonelsewhere, including from Queen Charlotte City toTlell, at Port Clements, Tow Hill, Peel Inlet,Moresby Camp, and half the saplings were defoliatedover 2 ha at a campsite at Peel Inlet.

True Fir Pests

BudwormsChoristoneura spp.

Defoliation of spruce and alpine fir forests by easternand 2-year-cycle budworms covered 245 400 ha and34 350 ha, respectively, in parts of four forestregions in 1991 (Map 5).

Defoliation of current foliage and some olderfoliage of white spruce and alpine fir by easternspruce budworm, Choristoneura fumiferana, wasmapped in more than 135 separate patches north andwest of Fort Nelson totaling more than 245 000 ha.This is down 40% from the area affected in 1990, aspredicted, but it is still double the area defoliated in1989. Defoliation extended into the Northwest andYukon territories. Defoliation, which occurred insome areas for the seventh consecutive year, waslight over 90% of the affected area, and moderateover the remainder. Most moderate defoliation wasnear Liard Hot Springs, and light defoliation waswidespread in the Fort Nelson River Valley betweenKlua and Cridland creeks.

Populations are expected to persist in 1992 inmany previously defoliated stands in the Liard andFort Nelson river drainages. This prediction is basedon egg masses on spruce foliage at two sites in theSnake River drainage, at one site in the Liard Riverdrainage, and at Clarke Lake.

Two aerial applications of a commercialformulation of Bacillus thuringiensis var. kurstaki

were completed by the British Columbia ForestService to protect mature spruce seed productionstands and adjacent young stands near Fort Nelson.Five blocks totaling 525 ha at three locations weretreated with (Dipel (R) 132).

Defoliation of spruce and alpine fir forests by 2-year cycle spruce budworm, Choristoneura biennis,was generally light over 34 350 ha in 104 separateinfestations in three forest regions. This was upslightly from 30 000 ha in 170 infestations in 1990.

Mature 'off-cycle' budworm defoliated alpinefir and spruce over 6775 ha near Keefer Lake eastof Cherryville in the Kamloops Region. In theeastern part of the Nelson Region defoliationoccurred in the St. Mary River Valley and atBugaboo Creek over 1525 ha, but not at Dewar andVowell creeks. This was up from 5850 hadefoliated in 1989, the most recent year withmature larvae in these areas. For the first timesince the 1960s, mostly light defoliation wasmapped over 15 000 ha in the Omineca Riverdrainage between Duckling and Ominicetla creeksand at Ankwill Creek north of Fort St. James.Defoliation was also light over 8000 ha in theOspika and Davis river drainages north ofMackenzie, where defoliation was mapped for thefirst time in 1989 over 11 385 ha. Increasedpopulations north of Chapman Lake in the easternpart of the Prince Rupert Region lightly defoliatedstands over about 500 ha.

17

Immature 'on-cycle' budworm larvae lightlydefoliated current foliage of high-elevation fir andspruce over 250 ha in a patch near McBride in thePrince George Region, and on 3250 ha in more than40 stands in the eastern part of the Cariboo Region.Light defoliation in the Vermilion and White Riverdrainages in the East Kootenay, first recorded in1990, covered 1300 ha.

During 1991, 34% of the buds were infested inthe Vermilion River drainage, indicating increasingpopulations and potential light and occasionalmoderate defoliation in 1992 when larvae mature.Only 8% of the buds were infested in the WhiteRiver Valley, indicating declining populations.Further bud counts to determine population trendswill be completed in early 1992.

Populations continued to be monitored inrepresentative sites in four regions to improveidentification and monitoring methods. About 1600adult males (average 827 per trap) were collected in50 non-sticky traps at 10 sites in four regions, and upto 88 larvae (average 11) were collected per location.Further study is necessary before numbers can becorrelated with population damage and potential.

Western balsam bark beetleDryocoetes confusus

The areas of recently killed mature alpine fir mappedduring aerial surveys totaled 62 500 ha in more than1200 separate pockets in parts of all six forestregions, mostly in the Prince Rupert Forest Region.

Infestations, which have persisted in the PrinceRupert Region for many years, were mapped in morethan 240 areas totaling 48 000 ha. Most of the treemortality was in chronically infested mature stands inthe southern part of the region in the Ootsa, Whitesail,and Morice lakes areas, and to a lesser extent in theMcKendrick Pass area north of Smithers, nearCranberry Junction, and in the upper Skeena Riverdrainage. Surveys in the southern part of the MoriceTSA in 1990 found that up to 30% of the maturealpine fir volume had been killed in parts of theMosquito and Shelford Hills areas, in upper WalcottCreek, and near Dome Mountain. An estimated 3%of the mature alpine fir have been killed by the beetleover 17 300 ha in the Cassiar TSA since 1987.

Most mortality in the Prince George Region wasin chronically infested areas northeast and northwestof Prince George and in newly infested areasnorthwest of Fort St. James totaling 6900 ha in morethan 145 widespread patches. This was up frommore than 75 separate areas totaling 4000 ha in 1989when coverage was similar.

In other regions, areas containing recently killedalpine fir increased overall, to 865 ha in the CaribooRegion, to 1700 ha in the Kamloops Region, and to3850 ha in the Nelson Region, but declined slightlyin the Vancouver Region to 1100 ha in about 70patches.

Annual fluctuations in the areas containingrecently killed mature alpine fir are due in part to thelimited aerial surveys in the more remote areas, andin part to accuracy of detection of recently deadtrees, some of which retain reddened needles for atleast 5 years.

Fir engraver beetleScolytus ventralis

The number of semimature and mature grand firkilled by fir engraver beetles in the southern part ofthe Nelson Region declined following three years ofoutbreak. Only three patches of recent tree mortalitytotaling about 10 ha were mapped in the Pend-d'Oreille area of the West Kootenay. This is adecline from 1990 when widely scattered trees wereattacked, and from 1989 when 30 infestationstotaling 235 ha were mapped.

The number of recently killed grand fir alsodeclined in drainages north of Creston from Lockhartto Alkali creeks near Crawford Bay and at CrawfordCreek, where mortality of more than half the treeswas common in 1990. Armillaria root disease,Armillaria spp., was present in the recently deadtrees at most sites.

Populations are likely to remain endemic.Mortality of grand fir in 1992 will likely be low andwill be due mostly to infection by root disease ofstressed hosts.

A balsam shoot boring sawflyPleroneura sp.

As forecast, sawfly populations declined to endemiclevels in true firs at high elevations in the VancouverForest Region following three consecutive years ofdamage. Populations in grand fir near Creston declinedand only 35% of the shoots were destroyed, and therewas no damage near Nelway and Rossland where treeswere lightly infested over up to 2 ha in 1990.

Balsam woolly adelgidAdelges piceae

Active adelgid populations were found on 10-year-old and older amabilis fir at Lizzie Creek east ofLillooet Lake. Dieback and flat-topped crowns were

18

evident on adjacent mature and overmature trees.The area is slightly east of the quarantine zone insouthwestern British Columbia. It was the secondrecord of infested trees beyond the distribution andquarantine zones since 1987, and this is resulting in areview of the zone boundaries. Populations,however, were too low to cause any obvious damageto the regeneration.

Surveys of grand fir in the Nelson Region alongthe international border have not found the adelgid.Populations nearby in central Idaho increasedsignificantly in 1990 and infested pockets ofsubalpine and grand fir over 24 000 ha. There wasno evidence of the adelgid on two mature 'gouted'alpine fir in Nelson.

Hemlock Pests

Western blackheaded budwormAcleris gloverana

Budworm populations in previously defoliatedwestern hemlock near Holberg on northernVancouver Island collapsed as forecast. Populationsremained endemic in hemlock on the QueenCharlotte Islands and on alpine fir in the eastern partof the Prince Rupert Region following their collapsein 1989 and 1990, respectively. However,populations increased in the western part of thePrince Rupert Region. Alpine fir and white sprucewere moderately and severely defoliated over about1000 ha near Bare Loon Lake in the proposedChilkoot Trail National Park and white spruce werevery lightly defoliated over 10 ha in KinaskanProvincial Park in the upper Iskut River Valley.

Western hemlock looperLambdina fiscellaria lugubrosa

Populations of the western hemlock looper increasedgreatly and defoliated mostly old-growth westernhemlock in 266 patches totaling more than 50 000 hain the Cariboo and Nelson forest regions; defoliationoccured for the first time since 1984 in the KamloopsRegion, and for the first time since 1964 in the PrinceGeorge Region (Map 5). This was significantly moredamage than occurred in 1990, when only eightpatches totaling 1115 ha were defoliated.Defoliation was mostly light and moderate and wassevere on only about 10% of the area.

The major area of expanded defoliation wasover 36 235 ha in the Kamloops Region. Defoliationwas severe over 4200 ha in 10 separate infestationsfrom Blue River to the Albreda River, near TumtumLake in the Adams River drainage, and alongHobson Lake in Wells Gray Provincial Park. Areasof moderate defoliation covered 17 900 ha in 21widespread patches, and light defoliation occurred

on 14 000 ha in 65 patches throughout the NorthThompson and Adams river area including WellsGray Park. One patch of dead trees, attributed toprevious defoliation by the looper, covered about140 ha near Green Bush Lake at the headwaters ofthe Shuswap River. Earlier infestations resulted intree mortality and top-kill of mature hemlock.

In the Nelson Region, the area of defoliationexpanded eightfold to 8225 ha; light or moderatedefoliation occurred over 7150 ha and severedefoliation on 1075 ha along Revelstoke Lake fromFrisby Ridge to Mica including the Albert, Downie,Script, and Bigmouth creek drainages and east ofMica along McNaughton Lake to Wood Arm.

Infestations near Quesnel and Horsefly lakes inthe Cariboo Region increased to 25 areas totaling5700 ha, up from only 200 ha in 1990 the first yearof infestation. Defoliation was light over 5000 haand moderate over the remainder on the LynxPeninsula, east of Quesnel Lake from Killdog Creekto Stranger Lake, and from Horsefly Lake east toBouldery Creek.

Mature hemlock and cedar were severelydefoliated over about 250 ha at Hankins Creeksoutheast of McBride. This defoliation was the firstby this defoliator recorded in the area since 1955,when patches of severe defoliation from Giscombeto McBride were recorded over 48 000 ha.

Defoliation is forecast to be severe in 1992 at11 of 25 sites sampled in three regions in 1991.Moderate defoliation is forecast at two sites and lightor trace defoliation at the remainder. In the NelsonRegion defoliation is forcast to be severe at 5 of 15sites, including Bigmouth and Downie creeks again,and at Mica, Redrock Harbour, and GoldstreamRiver (Map 6). Moderate defoliation is forecast atTangier River with light or trace at nine sites westand south of Revelstoke. This forecast is based onan average of 85 looper eggs (range 2-363) persample of lichen from each site. In the Kamloops

19

Map 6. Defoliation by western hemlock looper forecast for 1992, based on 1991 egg surveys.

BRITISH COLUMBIA

0 100 200 km

Q Trace

O Light

Moderate• Severe

Region, severe defoliation is forecast at five of sevensample sites and light defoliation is forecast at theremainder (average 89 eggs per sample, range 15-162) in the Adams and North Thompson riverdrainages. In the Cariboo Region, where an averageof 37 eggs were found per lichen sample (range 4-71), defoliation is forecast to be severe on the LynxPeninsula area of Quesnel Lake; moderatedefoliation is forecast at one site at Boulder Creek,but only trace defoliation is forecast at a second site.

Larval and pupal mortality from parasitism wasless than 1% of the population at three sample sitesnorth of Revelstoke. This compares with 34% in theprevious infestation in 1983, which resulted in thecollapse of populations in 1984.

Gray spruce looperCaripeta divisata

Defoliation of mostly western hemlock and westernred cedar, and some other coniferous species, by the

looper in the western part of the Nelson ForestRegion increased almost threefold to 3850 ha in 34separate patches (Map 5), up from 1370 ha the firstyear of the outbreak in 1990.

Defoliation, mostly near Arrow, Slocan, Box,and Duncan lakes, was moderate over 2735 ha andlight over 1115 ha. Most of the moderatelydefoliated patches were on the west side of UpperArrow Lake. Elsewhere, defoliation was light inwidespread scattered patches on the west side ofSlocan Lake including Valahalla Provincial Park,and near Box and Duncan lakes. Damageassessments of hemlock stands severely defoliated in1990 found 12% of the trees killed in two stands,top-kill on 70% of the trees, and dieback of the mid-crown on 22% of the trees.

Larval mortality at four sites averaged 72%(although this may in part be due to contamination), upfrom 27% in 1990. Mortality was caused mostly bypathogens, Entomophaga sp. and Paecilomyces sp.,which should reduce populations significantly in 1992.

Larch Pests

Larch casebearerColeophora laricella

Larch casebearer populations in western larch standsin southeastern British Columbia increased slightlyoverall.

Trace to light defoliation and small patches ofmoderate defoliation were again common in the hostrange in drainages from Oliver to Cherryville andeast of Osoyoos in the eastern part of the KamloopsForest Region. Low populations continued nearSicamous where they were first recorded in 1990.

Populations increased slightly overall in the EastKootenay part of the Nelson Region, particularlynear Creston where stands over 450 ha at SummitCreek and over 100 ha at Mt. Rykerts and EastArrow Creek were lightly defoliated. Defoliation inthe West Kootenay was generally trace or lightthroughout the host range. This was less severe thanthe defoliation recorded in 1990.

At most of the 18 long-term parasite releasestudy sites in the Nelson Region, and at two sitesin the adjacent Kamloops Region, defoliation wastrace to generally light. At sites near Castlegar andVernon, defoliation was light and moderate,respectively, where defoliation was severe in1990.

Larval parasitism, mostly by the introducedAgathis pumila and also by Chrysocharislaricinellae, averaged 10%, similar to parasitismlevels in 1990 and 1989. Parasitism of casebearerpupae decreased slightly to 10% (range 0-48%) from14% in 1990 (L. Humble and I. Otvos, ForestryCanada, Victoria, personal communication).

After several consecutive years of lowpopulations attributed to the success of parasitereleases, sampling of overwintering larvae todetermine populations and to forecast defoliationwas discontinued in 1990. More than 15 000specimens of C. laricinellae or A. pumila have beenreleased in the biological control program againstlarch casebearer from 1966 to 1987.

Larch sawflyPristiphora erichsonii

Populations of larch sawfly continued to declinealmost to endemic levels in most previouslydefoliated tamarack stands in northern BritishColumbia, in the southwestern part of the YukonTerritory, and in exotic larch plantings in central andsouthwestern British Columbia, but remainedendemic in western larch stands in the NelsonRegion.

Tamarack at French River in the northern part ofthe Prince Rupert Region near the Yukon border andalong the Robert Campbell Highway in the YukonTerritory were very lightly defoliated. This followeda significant decline in populations in 1990.

Small groups of larch in Stanley Park inVancouver were lightly defoliated for the thirdconsecutive year but less severely than in 1989, thefirst year defoliation was recorded by FIDS in thearea. At the University of British ColumbiaResearch Forest near Haney, declining populationslightly defoliated exotic larch for a fourth year. AtTerrace and Prince George, populations wereendemic following defoliation of exotic larch forthree consecutive years.

Green larch looperSemiothisa sexmaculata

Larch looper populations in western larch stands in theWest Kootenay from Creston to Fauquier collapsedfollowing patchy defoliation of western larch totaling 12000 ha in 1990, the first year of infestation since 1977.Larval parasitism in 1990 averaged 32%, and pupalparasitism was 12%. These levels were considered toolow to eliminate populations, and the number ofoverwintering pupae indicated light defoliation in 1991;however, populations did not develop.

Larch needle diseasesHypodermella laricis

Meria laricis

New infections and discoloration of western larch bylarch needle diseases were conspicuous andwidespread throughout much of the host range in theNelson and Kamloops forest regions for the secondconsecutive year. Foliage discoloration was

generally moderate but with severe browning inpatches up to 800 ha. These diseases have fluctuatedperiodically with weather conditions.

In the Nelson Forest Region, patches of westernlarch discolored by M. laricis totaled nearly 10 000ha in about 80 separate areas scattered across thehost range. Patches of severe and moderatediscoloration were common, particularly in thesouthern part of the East Kootenay, in the BoundaryTSA and in the southern parts of the Arrow andKootenay Lake TSAs in the West Kootenay.

In the Kamloops Region, discoloration of all ageclasses of western larch increased throughout theOkanagan TSA, and from Canoe to Sicamous in theKamloops Region. From 30 to 100% of immatureand mature trees were severely discoloredparticularly on north facing slopes, at widespreadlocations east of Vernon, in the Shuswap RiverValley, near Mabel Lake, from Canoe to Sicamous,and west of Spallumacheen.

A larch shoot minerArgyresthia columbiana

Populations of a shoot miner, which killed newshoots of young western larch at Brewer Creek nearDutch Creek in 1990, increased significantly in 10-to 15-year-old larch in a spaced stand and killed 40%of the tips on 75% of the trees.

European larch cankerLachnellula willkommii

There has been no evidence of this potentiallydamaging canker in western, alpine, eastern, orexotic larch stands in British Columbia. A nativelarch canker continues to be found on immaturewestern larch only in a few widely scattered sites inparts of the Nelson Forest Region.

Multiple Host Pests

Black army cutwormActebia fennica

Cutworm populations generally remained at lowlevels in recently burned and planted sites in interiorBritish Columbia in 1991. This was similar topopulation levels in the previous two years.Recently planted seedlings were lightly defoliated atonly 4 of 44 sites surveyed in three forest regions.

These included a site slash-burned in the fall of 1990southeast of Prince George, two sites in the westernpart of the Prince Rupert Region, and one site in theeastern part of the Nelson Region. Elsewhere, larvaewere common on deciduous ground cover at anadditional 7 of 20 sites in the Prince Rupert Region,and at 2 of 10 sites in the Nelson Region. Mothcatches at these sites in 1990 ranged from 210 to 613(average 432).

Population declines in 1989 and 1990 wereattributed to natural factors, an entomopathogen andnatural parasites which reduced larval populations byup to 53% and reduced pupae by 47%. Larvalmortality in 1991 was mainly due to diseases,Verticillium sp., Fusarium sp., and Paecilomyces. Only8% of the larvae were parasitized, mostly by Diptera.

In the Nelson Region, cutworm larvae severelydefoliated half the Engelmann spruce seedlingsplanted in 1991 over 10 ha at Vowell Creek in theEast Kootenay. Ground cover was lightly defoliatedover an adjacent 10 ha where 613 male adults weretrapped in 1990. The number of pupae ranged from10 to 50 per 1000 cm 2 , which is similar to thenumbers of pupae found in 1990, and whichindicates continuing populations in 1992. Follow-upsurveys of western larch defoliated by cutworm in1990 found dead terminal shoots and new growthlimited to the base, resulting in bushy growth. AtSwan Creek on the west side of McNaughton Lake,herbaceous ground cover was also lightly defoliatedwhere 535 males were trapped in 1990, but there wasno damage to recently planted seedlings. In the WestKootenay, fireweed was lightly defoliated at one ofeight sites examined north of Revelstoke, but larvaewere too few to damage seedlings.

In the Prince Rupert Region, cutworm larvaelightly defoliated recently planted seedlings in tworecently burned sites near Meziadin Lake in thewestern part of the region. Fireweed and otherherbaceous ground cover were lightly defoliated atan additional 7 of 20 sites surveyed in the region,mostly in the Meziadin Lake area where 150-550moths were trapped (average 340/trap) in 1990.

In the Prince George Region, cutworm larvaeseverely defoliated ground cover over 1 ha within a400-ha recently burned and planted site at HamboneLake southeast of Prince George. About 770 maleadults were trapped at the site in 1990. There was noevidence of larval populations at an additional ninesites surveyed in 1991, where up to 572 males hadbeen trapped last year.

Based on the numbers of male adults inpheromone-baited sticky traps, cutworm larvae couldpose a threat to seedlings planted in 1992 in areasthat were slash burned in 1990-91. More than 600males were trapped at 6 of 65 trap sites in parts ofthree regions. All six sites were in the Prince RupertRegion, the highest catch (1167 moths) occurrednear Chapman Lake north of Smithers. A predictivewarning system linking moth catches withsubsequent defoliation of seedlings and vegetation iscurrently in press (R. Shepherd, Forestry Canada,Victoria, personal communication).

Rhizina root diseaseRhizina undulata

Fruiting bodies of Rhizina root disease weregenerally less numerous and widespread andseedling mortality was significantly lower than in1990 in parts of the Nelson and Prince Rupert forestregions. This was the fourth and lightest year ofseedling mortality caused by this disease in thePacific and Yukon Region.

Seedling mortality in the Prince Rupert Regionin 1991 declined significantly from an average of13% in 1990. This was due to planned delays inplanting where fruiting bodies had been present in1990 or 1989. Fruiting bodies were found in 12 of15 previously burned areas in the western part of theregion but only 2% of the seedlings were infected attwo of the three sites planted this year. Fruitingbodies and very small numbers of recently killedseedlings were found in 2 of 18 sites surveyed in theeastern part of the region.

In the Nelson Region, 1 to 30% (average 12%)of the seedlings were killed at 5 of 10 recentlyburned and planted sites surveyed in the WestKootenay, compared with 27% of the seedlingskilled in four sites in 1990. Fruiting bodies werecommon in an additional unplanted area, and at oneof five planted sites in the eastern part of the region,but seedlings were not affected.

Year-old sporophores were still present in partof a burned and planted site west of Clearwater in theKamloops Region where seedling mortality occurredin 1990, but none was found at another 10 recentlyburned areas.

The presence of new fruiting bodies in parts oftwo forest regions in 1991 could provide inoculum toinfect some recently burned adjacent sites in 1992.Delay of planting where fruiting bodies are presentcould reduce losses.

Pests of young stands

More than 250 young 2- to 25-year-old natural andplanted conifer stands established or treated underthe first Canada/B.C. Forest Resources DevelopmentAgreement were surveyed in British Columbia in1991. This was part of a continuing study to identifymajor pests and environmentally related problemsand their impact on young stands.

At each location, at least seven trees wereexamined in each of at least 10 circular plots. Intotal more than 28 000 trees were examined. Pineswere the major component in about 41% of the sites,spruce in 20%, Douglas-fir in 20%, hemlock in 3%,

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Table 2. Number of young stands by region and species examined in British Columbia in 1991

Species

Region Total Pine Douglas-fir Spruce Hemlock Other'

Cariboo 27 11 8 4 4Kamloops 44 26 1 10 7Nelson 46 17 14 9 6Prince George 53 29 1 19 4Prince Rupert 40 20 9 11Vancouver 39 - 27 5 7Q.C. Islands 3 3

Total 252 103 51 51 8 39

(%) (41) (20) (20) (3) (16)

1 Includes plots in which the major component is not listed above, e.g., western larch, western red cedar, true firs, or where

species are equal components.

true firs, cedar, larch and other species includingtrembling aspen and poplar comprised the remainder(Table 2).

About 60% of the 252 stands surveyed wereeither free of pests or contained only insects ordiseases of no consequence. The remaining 40%contained pests which caused significant damageincluding tree mortality, but usually less than 10% ofthe trees were affected. Locally significant anddamaging were root diseases, terminal and rootcollar weevils, and stem rust cankers. Lesssignificant but widespread problems included theeffects of year-old and new climatic injury, mammalfeeding, and infection of new and older needles bynative diseases.

Tree mortality caused by root diseases includingArmillaria, Armillaria spp., and blackstain,Leptographium wageneri, averaged 4% (range 1-12%) of the conifers in 8% the stands examined,mostly in the eastern part of the Nelson ForestRegion.

Spruce weevil, Pissodes strobi, infested 8%(range 1-46%) of the terminals in 33% of 51 spruceplantations particularly in the western part of thePrince Rupert Region, where terminal leadermortality was higher than average at 12% in fivestands. Current attack of 9 and 29% of the terminalswas found at two sites in the eastern part of theCariboo Region. An average of 4% (range 1-15%)of the terminals in 7% of the immature lodgepolepine plantations in five regions were attacked andkilled by lodgepole pine terminal, P. terminalis, in

1991. The highest incidence of this weevil was inthe eastern part of the Prince Rupert Region. Anaverage of 5% (range 1-32%) of the immaturelodgepole pine in 24% of the pine plantations wereinfested by Warrens root collar weevil, Hylobiuswarreni. The highest level of damage was partialbasal girdling of 32% of the trees at Andimaul Creekin the eastern part of the Prince Rupert Region.Mortality of immature lodgepole pine in nearbyareas in previous years reached 15% and more than75% were partially girdled. In the Prince GeorgeRegion, 3% (range 1-14%) of the trees were infestedin 13 plantations.

Stem and branch diseases including western gallrust, Endocronartium harknessii, blister rusts,Cronartium spp., and Atropellis cankers, Atropellisspp., were common in pine plantations surveyed, buton average these diseases infected less than 5% ofthe trees. Western gall rust, Endocronartiumharknessii, was common in 60% of the stands butinfected an average of only 4% (range 1-12%) of thetrees, and generally there was little impact onstocking levels. Blister rusts, Cronartium spp.,infected an average of 5% (range 1-12%) of theimmature lodgepole pine at 17 sites in parts of threeforest regions, mostly west of Prince George and inthe eastern part of the Prince Rupert Region.Infections were primarily on stems but tree mortality,frequently the result of perennial stem cankers, wasgenerally less than 1%. White pine blister rust,C. ribicola, infected an average of 2% (range 1-6%)of the white pine in seven plantations in three forest

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regions, but most of the infections were in theVancouver Region. Atropellis stem cankers,Atropellis spp., infected 5% of the 25-year-oldlodgepole pine in 15 stands mostly in the PrinceGeorge Region and the eastern part of the PrinceRupert Region.

Buds killed by recent early and late frosts andcold winds often resulted in multiple tops. This typeof damage affected 15% (range 1-84%) of theconifers in about 75% of the young stands mostly inthe Cariboo, Prince George, and Prince Rupertregions.

Feeding by a variety of mammals debarkedstems and branches of conifers in 37% of the youngstands surveyed. However, stocking levels were notseriously reduced except occasionally by porcupinesand voles (see 'Mammal damage' page 27).

Foliar diseases infected and discolored both newand old needles of conifers in about 30% of theyoung stands surveyed. Most moderate and severeinfections resulted in premature needle loss, butcaused little change in vigor or form. The foliardiseases were most common on pines. The mostcommon disease on pines was a needle cast,Lophodermella concolor. Less common were redband needle disease, Dothistroma (Scirrhia) pini,and Elytroderma deformans. Fir-fireweed rust,Pucciniastrum epilobii, discolored new foliage on upto 45% of the true firs in 20 plantations, most ofthem north of Prince George.

Lodgepole pine dwarf mistletoe, Arceuthobiumamericanum, infected young lodgepole pine in onlytwo plantations. The stems and branches on 2% ofthe 14-year-old trees at Mackin Creek, west ofWilliams Lake in the Cariboo Region, were infecteddue to the proximity of severely infected overstory.One percent of the pine were infected at WhistleCreek near Hedley in the southern part of theKamloops Region.

The most common pest of Douglas-fir wasCooley spruce gall adelgid, Adelges cooleyi,although it did not significantly affect tree growthand vigor or tree form. Also common but of littleconsequence were spruce gall adelgid, Pineus sp.,which was common in 60% of the spruce stands andgiant conifer aphid, Cinara sp., which was found on3% (range 1-9%) of the conifers at nine sites.

Defoliator larvae were common but they weretoo few to cause significant damage. These includedwestern spruce budworm, Choristoneuraoccidentalis, and 2-year-cycle budworm, C. biennis.

Lodgepole pine, some Scots pine, Siberianlarch, and Norway spruce seedlings planted in 1986were examined at four sites in the Prince George

Region and at one site in the Yukon Territory as partof a cooperative international survey with SvenskaCellulose of pest losses on different provenances.Bud mortality caused by frost, snow, ice, and coldwinds resulting in multiple tops and bushy form wascommon at three sites in the northern part of thePrince George Region. An average of 35% (range20-45%) of the Siberian larch were affected at threesites, 5 and 80% of the lodgepole pine at each oftwo sites, and 90% of the Norway spruce wereaffected at one site near Fort Nelson. Western gallrust, Endocronartium harknessii, infected stems andbranches on 5% (range 1-10%) of the trees at allfour plots in the Prince George Region. Stemcankers of blister rust, Cronartium coleosporioidesand C. comandrae, infected 12% of the lodgepole pine atNation Bay near Mackenzie, where Warren's rootcollar weevil, Hylobius warreni, also girdled andkilled 3% of the trees this year. Stalactiform rustalso infected 2% of the lodgepole pine at sites nearTerrace and Dease Lake in the western part of thePrince Rupert Region. Increased numbers ofnorthern pitch twig moth, Petrova albicapitana,lightly infested 2% of the stems of trees in plots nearMackenzie and Fort Nelson. Increased populationsof gouty pitch midge, Cecidomyia piniinopis,populations infested an average of 6% (range 1-10%) of the new shoots on about 16% of the pinenear Fort St. James, but none was infested near FortNelson where 1% of the trees were infested lastyear. All the Siberian larch and Norway spruce atthe plot near Fort Nelson again had only tracedefoliation from a few larvae of eastern sprucebudworm, Choristoneura fumiferana, which isepidemic in the area. About 10% of the 1-year-oldneedles on 30 to 40% of the lodgepole and Scotspine at the Teardrop Road plot near Fort St. Jameswere chlorotic, which may have been due to anutrient deficiency.

About 22% of the Siberian larch and 6% of thelodgepole pine in the Takhini Forest Reserve plotnear Whitehorse have been killed, mostly by plantingshock and by successive years of winter damage.Stems on an additional 60% of the pines around theplot perimeter were clipped off by snowshoe hares,Lepus sp., leaving only the first whorl on about 25%of the trees. Adjacent larch, which had beendamaged by feeding, average only 10 cm in heightafter five growing seasons.

Seed orchard and nursery pests

Surveys of foliar insects and diseases on seedorchard trees continued in 1991. Assessments of

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cone and seed insects and diseases in seed orchardswere discontinued in 1989.

Thirteen coastal seed orchards were surveyed in1991. Douglas-fir was the most common treespecies in nine orchards, western hemlock the mostcommon at six orchards, amabilis fir at four, andpoplar at three; western red and yellow cedars, Sitkaspruce, lodgepole and white pine, and noble fir werein only one or two seed orchards.

The most common pest on Douglas-fir wasCooley spruce gall adelgid, Adelges cooleyi, whichlightly and sometimes moderately infested mostDouglas-fir in seven of nine orchards and 1 to 10%of the tips on 75 to 80% of the spruce at twoorchards. A very few larvae of western sprucebudworm, Choristoneura occidentalis, werecommon in three orchards, but no damage wasobserved. Balsam woolly adelgid, Adelges piceae,was common on amabilis fir in two of four orchards,and balsam twig aphid, Mindarus abietinus,deformed 20% of the needles and twigs on about halfof the amabilis fir at one orchard. Sitka spruce attwo orchards were lightly infested by A. cooleyi, butnot by green spruce aphid, Elatobium abietinum,which had infested 70% of the trees at three orchardsin 1990. There was no additional damage to yellowcedar by a gall midge which declined in 1990 due toparasitism after three years of severe damage in twoorchards. Hemlock woolly adelgid, Adelges tsugae,remained endemic in four orchards and lightlyinfested western hemlock at two orchards. Yellowblisters on poplar leaves caused by Taphrinapopulina were common on up to 20% of the leaveson up to half the trees at three orchards.

In forest nurseries, several thousand western redcedar seedlings were killed by increased severeinfection by a leaf blight, Didymascella (Keithia)thujina. Seedling root rots, Fusarium sp. andPythium sp., and shoot blight caused by Botrytis sp.,were less common on nursery stock than in 1990.Sirococcus strobilinus, was not found on westernhemlock seedlings and seeds in 1991 in BritishColumbia, where it was found on seedlings for thefirst time in 1990.

Forest tree seed collected for international tradein British Columbia and Yukon Territory is certifiedunder the Organization for Economic Cooperationand Development (OECD). In 1991 a total of 700hectolitres of cones of 10 coniferous species (mainlySitka spruce with lesser amounts of pines, spruce,and firs) and 10 hectolitres of alder were certified forexport. The value of the seed extracted from thesecones exceeds $750 000.

Root diseasesArmillaria spp.

Inonotus tomentosusLeptographium wageneri

Phellinus wierii

Surveys of ten mature stands in two drainages in theEngelmann Spruce-Subalpine Fir (ESSF)biogeoclimatic zone in the East Kootenay part of theNelson Region found that 42% of the trees had beenkilled by root diseases or had symptoms of infection.An additional 32% of the trees were infected but didnot show external symptoms of infection. Recentmortality of Douglas-fir killed by Armillaria rootdisease, Armillaria ostoyae, in a park near Kamloopsresulted in stand openings near campsites. Mortalityof mature lodgepole killed by blackstain root disease,L. wageneri, was common in parts of the NorthThompson River Valley. Mature and immatureDouglas-fir were killed by root diseases atwidespread locations throughout the VancouverRegion.

In ten representative stands in the EastKootenay, tree mortality caused mostly by Inonotustomentosus and to a lesser extent by Armillariaostoyae, was highest in Engelmann spruce andlodgepole pine in the middle fork of the White Riverdrainage where 96% of the spruce and 85% of thepine were dead or dying. The remaining 4% of thespruce were infected but showed no symptoms.Nearly half (46%) of the mature lodgepole pine atAngus Creek, one of six sites surveyed in the St.Mary River drainage, were dead or dying and anadditional 51% were infected but showed no externalsymptoms. Additionally, surveys of maturelodgepole pine at Quartz Creek west of Goldenfound that 10% of the trees had been killed and anadditional were 6% infected by blackstain rootdisease, L. wageneri. These infections were asignificant extension of the eastward range ofpreviously known areas of infected pine, and wereassociated with trees attacked by pine engraverbeetle, Ips pini. Elsewhere in the Nelson Region, 60-to 80-year-old grand fir and Douglas-fir in pocketsalong the Pend-d'Orielle Valley were recently killed,mostly by Armillaria root disease and to a lesserextent by blackstain root disease. Armillaria rootdisease also killed 35% of the lodgepole pine in a1987 plantation at Skeff Creek west of Grand Forks,where blackstain root disease was also present.

In the Kamloops Region, recent mortality ofmature lodgepole pine, Engelmann spruce andDouglas-fir infected by Armillaria root disease

26

resulted in stand openings adjacent to campsites atPaul Lake Provincial Park. Elsewhere, blackstaininfected and killed about 20% of the mature pine inpatches west of Darfield in the North ThompsonRiver Valley.

Mature and immature Douglas-fir killed recentlyby Phellinus root disease were common in theVancouver Region in the Chehalis River drainagenear Squamish, and at Harrison Lake, Mission, andGibsons. Numerous recently dead standing maturetrees occurred in pockets near stumps and windthrowthroughout a heavily used recreational campsite nearRoberts Creek on the Sunshine Coast. Armillariaroot disease killed up to 25% of the semimature andyoung trees in small patches in six surveyed areas inthe Vancouver Region. The highest mortality was atMowhokam Creek near Boston Bar, and occurredalso, but less commonly in the University of BritishColumbia and Seymour demonstration forests, in theCapilano watershed, and near Sechelt and PowellRiver.

Mammal damage

Feeding damage to recently planted coniferousseedlings and immature trees by a variety ofmammals increased significantly in 1991 in parts ofsix forest regions and Yukon Territory.

Voles

High numbers of meadow voles, Microtus sp., killedup to 20% of the recently planted stock in aplantation on the east side of Babine Lake in thePrince Rupert Region. Damage was common butless severe at an additional eight sites. This occurredduring the winter and followed significant populationincreases in 1990. At Salvus Creek west of Terrace,39% and 15% of the seedlings were killed orpartially girdled at each of two plantations.Elsewhere in the region, stems were partially girdledand leaders and laterals were clipped on a smallnumber of stems at one site, and roadside lodgepolepine and deciduous seedlings were killed or strippedat two sites between Meziadin Lake and CranberryRiver.

About 24% of the spruce seedlings were girdledand killed in a recently planted site at Ensign Creeknorth of Golden in the Nelson Region. None wasdamaged at Redding Creek west of Kimberley wheregroups of seedlings were killed in 1990.

Increased vole populations in parts of theCariboo Region killed about 40% of the lodgepolepine and some Douglas-fir seedlings in a planted

area at Leeches Lake west of Williams Lake.Recently planted seedlings in the Kimsquit Riverdrainage north of Bella Coola were killed by voles.This was the first record of significant damage in thearea.

At Callaghan Creek near Squamish, about 75%of the Douglas-fir planted in 1989 were dead whensurveyed in 1991. Mortality was attributed todebarking by voles in 1989-90. There was noevidence of new feeding at Twin One Creek south ofPemberton, where seedlings were debarked andkilled in 1990.

Porcupines

Young and semimature conifers continue to be killedby porcupines, particularly in the western part of thePrince Rupert Region where patches of stem andbranch bark have been chewed annually. This hasbeen a significant factor in reducing stocking levelsparticularly in spaced lodgepole pine and westernhemlock stands. In 1991 tree mortality or debarkingwas recorded in 50 widely scattered areas totalingabout 725 ha. About 33% of the mostly dominantand codominant conifers were top-killed and anadditional 9% were partially girdled in a 15-year-oldplantation at Shames River west of Terrace. Anaverage of 64% of the amabilis fir, 28% of thehemlock, and 6% of the Sitka spruce had dead tops.Northwest of Terrace, 10% of the immature to semi-mature alpine fir and western hemlock were killedover 100 ha at Luncheon Creek and 1% were killedover 25 ha at Erlandsen Creek. Half the trees at bothsites were top-killed. At the south end of Lava Lake,about 30% of the naturally regenerated lodgepolepine were totally or partially girdled in one smallpatch. About 10% of 30-year-old codominanttrembling aspen in a 5-ha patch at Sedan Creek westof Kitwanga were partially girdled but not yet killed.

Squirrels

Feeding by increased squirrel populations in theCariboo Region resulted in highly visible branch tipmortality on lodgepole pine. One to thirty 'flagged'branches per tree in pockets of 0.2 to 0.5 ha werecommon in the southern and western parts of theregion. Feeding on healthy and dwarf mistletoe-infected lodgepole pine was common, particularlyfrom 70 Mile House to Lac la Hache and fromAnahim to Tatla Lake.

An estimated 55% of the recently plantedlodgepole pine seedlings were killed by groundsquirrels over 55 ha near Barriere Mountain in the

27

Kamloops Region. An additional 30% were killedover 5 ha near Coldscaur Lake in the NorthThompson River Valley, where seedling mortalityoccurred in 1990.

Squirrels debarked and killed 10% and damageda further 80% of the young spaced lodgepole pine ata site at Bobtail Creek, southwest of Prince George.

Partial branch girdling of immature lodgepolepine was more common than in 1990 in parts of theYukon Territory. About five branch tips weredebarked on 10% of the trees, usually in dense standsfrom Watson Lake in the Yukon Territory to SwiftRiver in the northern part of the Prince RupertRegion, and to a lesser extent near Boya and Deaselakes. Hares clipped the stems of conifers along roadedges near Whitehorse, the south end of the CanolRoad, and near Johnsons Crosssing.

Climatic injury

Following severe discoloration by strong cold windsin early 1989, recovery of most conifers in parts ofsix forest regions continued. There was no increasein mortality of hemlock and cedar near Bella Coolaand mature lodgepole pine south of Fernie. Winterdamage to conifers was widespread in the YukonTerritory for a third consecutive year.

There was little evidence of permanent damageto conifers in the eastern part of the Cariboo Regionand near Bella Coola and along Burke Channel toKing Island where a new flush occurred in late 1989.Signs of recovery had been evident in 1990.However, small patches of tree mortality and budmortality were common over 250 ha west of Lac LaHache. Recovery of previously discolored coniferswas common in most regions and was evident in thefollowing areas: in the Kamloops Region, particularlyin the Highland Valley, in Wells Gray ProvincialPark, and Vavenby; in the eastern part of the NelsonRegion, in the Flathead and Elk river drainages, theWigwam, Couldrey, and Kishinena creek valleys, andin the Bush River Valley and in Glacier NationalPark; east of Prince George to McBride, at TumuchCreek, along the Bowron River Valley, and in theTorpy River drainage; in the Prince Rupert Regionalong the Skeena River Valleyand near Fulton Lakein the eastern part of the region.

Climatic injury to conifers in 1991 was mostsevere and widespread in the Yukon Territory. Lowtemperatures, often accompanied by strong winds,caused needle discoloration, terminal and branchdieback and occasionally tree mortality of spruce andto a lesser extent other conifers. This has occurredfor at least five consecutive years at widespread

locations throughout the Yukon Territory. Mostdamage was along Little Atlin Lake, along the AlcanHighway from Burwash Landing to Beaver Creek,and along the Klondike Highway north of StewartCrossing to Carmacks. About 5% of needles onimmature lodgepole pine at Takhini were discolored,and 10 to 80% (average 40%) of the older needleswere 'winter flecked' for 5 km near km 1367 on theAlcan Highway. An average of 20% of the year-oldalpine fir needles were killed over 5 ha north ofJohnstons Crossing and 10% of the new buds ontamarack along the Campbell Highway north ofWatson lake were killed by late frost.

Roadside conifer mortality

New tree mortality, crown and branch dieback, andfoliage discoloration of conifers along pavedhighways and access roads declined overall in theCariboo, Nelson, and Prince George regions butincreased in localized areas of the Kamloops Region.

Damage caused by a combination of site, saltinjury, and moisture stress was less common than in1990 in the Cariboo Region, where Douglas-fir,lodgepole pine, and spruce had been severelyaffected along many highways in 1989. Recentdamage occurred in about 150 widely separatedpatches along most major highways in the region,and at a municipal park at Williams Lake.

Recent tree mortality and foliar discolorationof Douglas-fir and some lodgepole pin wasminimal in the East Kootenay. Similarly,discolored roadside cedar, pine, Douglas-fir, andspruce were less numerous in the West Kootenayfrom Nancy Greene Lake to Grand Forks, fromRock Creek to Beaverdell, and along the ChristianValley Road.

There was little or no discoloration of roadsideconifers by winter salt in the Prince George Regionwhere such damage was widespread in 1989-1990.

Douglas-fir as well as lodgepole and someponderosa pine adjacent to roads in parts of theKamloops Region were killed, severely discolored,and occasionally predisposed to attack by barkbeetles by winter salt accumulations. Most affectedtrees were in small widespread patches nearAnarchist Mountain, Westwold, Carquille, and inFountain Valley near Lytton.

Acid rain monitoring

There was no change attributable to acid rain in thecondition of trees and ground cover at 15 permanentsample plots across British Columbia monitored in

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1991. Mortality from causes other than acid rainaveraged 3% of the trees in seven plots mostly in theVancouver Region. Mortality was attributed tosuppression, to the root disease Armillaria ostoyae,or to blowdown.

Plots will be monitored closely because ofconcerns about potential acid rain and long-rangetransportation of air pollutants. However, to datethere is no scientific proof of damage caused by acidrain in western forests.

Deciduous and Ornamental Tree Pests

Tent caterpillarsMalacosoma spp.

Defoliation of trees and shrubs by forest tentcaterpillar, Malacosoma disstria, in parts of threeforest regions covered about 131 000 ha (Map 5). Aspredicted, this is about half the area affected in 1990.Defoliation was less widespread near Prince Georgeand in the Peace River area, but increased nearMcBride, in the eastern part of the Cariboo Region,and in the northern part of the Kamloops Region.Populations of northern tent caterpillar,M. californicum pluviale, increased slightly in thePrince Rupert Region and defoliated 72 separatestands over 4260 ha near Terrace.

Declining forest tent caterpillar populationsnorthwest and south of Prince George defoliatedtrembling aspen and, to a lesser extent, otherdeciduous trees in 69 infestations over about 81 000 ha.Defoliation was mostly light and moderate, althoughthere were patches of severe defoliation around andwithin Prince George. Aspen were defoliated insome areas for the eighth year. Decliningpopulations in the Peace River area defoliated aspenin 37 areas over 4800 ha near Taylor, Farmington,and Pouce Coupe, a decline from the 35 600 hamapped in 1990. The area of aspen defoliated nearMcBride increased to over 6500 ha, up from 4450 hain 1990 and 260 ha in 1989 when the infestationbegan.

Trembling aspen were severely defoliated in theCariboo Region in 155 patches totaling 14 185 ha, athreefold increase from 1990. Defoliation wasmostly severe near Bridge and Canim lakes east of100 Mile House, near Quesnel and Horsefly lakes,and from near Horsefly to Williams Lake.Defoliation had occurred in some of these areas forfour consecutive years. Areas of defoliation in theKamloops Region doubled to 6500 ha in 38 separatepatches. Some stands from Barriere to Avola and inWells Gray Provincial Park, were defoliated for athird year, but populations declined near Salmon

Arm, Skimikin, and Tappen where there was nosignificant defoliation. Populations collapsed in theNelson Region, as predicted, and remained endemicin the Vancouver Region near Chilliwack.

Defoliation of trembling aspen, cottonwood andother deciduous trees and shrubs is forecast tocontinue in 1992 in most recently infested stands, butthe extent and intensity of defoliation will generallydecline. The average number of new egg massesdeclined at 15 sites in the Prince George Region tothree per tree (range 1-16), down from 17 in 1990and 38 in 1989. Generally light defoliation isforecast near Prince George and in the Peace Riverarea, but moderate and severe defoliation is forecastnear McBride and Tete Jaune where an average of 11new egg masses per tree (range 6-16) were found.More than 10 masses per tree usually indicate severedefoliation. In the eastern part of the CaribooRegion, where an average of 13 egg masses werefound per tree (range 1-49) severe defoliation isforecast at two sites, moderate defoliation at twosites, and light defoliation is forecast at three sitesbetween Horsefly, Likely, and Quesnel. Defoliationis expected to continue in adjacent parts of theKamloops Region.

Larval parasitism and disease at nine sites in tworegions averaged 21%. The increased level ofparasitism (there were less than 5% in 1990)contributed to a decline of populations in some areas.

Increased northern tent caterpillar populationsdefoliated mostly black cottonwood over 4260 ha inmore than 70 separate patches in the western part ofthe Prince Rupert Region, up from 3200 ha in 1990.About 25% of the area was severely defoliated, and45% was moderately defoliated. Defoliation wasmore widspread near Terrace and in patches in theSkeena River Valley from the Kasiks to the Shamesrivers. Defoliation in the Wedeene River Valley,which occurred for the first time in this outbreak,was mostly severe.

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Large aspen tortrixChoristoneura conflictana

Trembling aspen were defoliated by large aspentortrix in parts of the Prince George Forest Regionand in southwestern Yukon Territory, in some areasfor the third consecutive year. In the Prince GeorgeRegion defoliation was mostly severe over about18 000 ha, up slightly from 16 465 ha in 1990. About45 separate patches of defoliation extended fromMackenzie to Fort Ware and along the AlaskaHighway from Fort St. John to Pink Mountain andwest of Fort Nelson at Steamboat Mountain. In theYukon Territory, defoliation was generally morewidespread but less severe than in 1990, particularlynear Whitehorse. Defoliation was mostly light butoccasionally severe in patches from Teslin west toTakhanne River Crossing.

Larval predation and parasite eggs on 5% of thelarvae in defoliated stands in the Yukon is still rarebut indicates a potential for partial reduction ofpopulations in 1992. Parasitism levels in 3- and 4-year-old infestations are expected to increase.

Gypsy mothLymantria dispar

About 72 adult male gypsy moths were trapped in 17areas in British Columbia in 1991. This compareswith 121 males in 16 areas in 1990. More than 8000sticky traps were monitored throughout BritishColumbia in 1991, the sixteenth year of a cooperativeprogram with Agriculture Canada (Plant Health),FIDS, and the British Columbia Forest Service.

Twelve of the 72 males have been confirmed byDNA analysis to be of the Asian strain, and 13 aresuspected to be the Asian strain of gypsy moth. Thisis the first known capture of this strain in NorthAmerica. Most were trapped in the Vancouver areain the vicinity of the Pacific National Exhibition, andsome were trapped in or near Stanley Park. Most ofthe remaining 47 males, likely of the Europeanstrain, were trapped at Parksville, Colwood, and thelower mainland.

For the fifth consecutive year male moths werecaught near Parksville (7), and for the thirdconsecutive year in West Vancouver (2), Vancouver(1), and the Saanich Peninsula (1). Catches weremade for the second consecutive year at Victoria (1),Colwood (5), Coquitlam (2), and Comox (3). Newcatches were made at Saltspring Island (3),Courtenay (3), Lynn Valley (7), Langley (3), Surrey(6), Aldergrove (1), Richmond (3), and at GoldenEars (1) and Alice Lake (1) provincial parks.

Only one male was caught on the SaanichPeninsula north of Victoria International Airport wherehigh trap catches (96 males) and numerous egg masses(37) were found in 1990. These high numbers of adultmales trapped in 1990 prompted aerial (113 ha) andground (40 ha) applications of Bacillus thuringiensisvar. kurstaki (Foray 48B) in late April and May 1991in an apparently successful eradication effort. Onlyseven males were captured at Parksville whereBacillus thuringiensis was applied aerially (over 85ha) and on the ground (over 7.5 ha) in 1990.

The captures at Golden Ears and Alice Lakeprovincial parks were in 2 of 305 traps set out byFIDS in 266 forested recreation areas in national andprovincial parks, commercial campgrounds, and nearmilitary bases beyond the lower mainland and majortowns.

Birch leaf minersLyonetia sp.

Fenusa pusillaProfenusa thomsoni

Bucculatrix canadensisella

Discoloration of native birch, particularly in theNelson Forest Region, by a leafminer, Lyonetia sp.,remained at very low levels following a significantdecline in 1990. Populations also declined atTerrace. Discoloration by Lyonetia sp., Profenusathomsoni, and Fenusa pusilla was less severe andwidespread in the Vancouver Region wherepopualtions had increased in the two previous years.Populations also declined at Smithers, and in PrinceGeorge where trees had been discolored for up tofive consecutive years.

Populations of amber-marked birch leafminer,Profenusa thomsoni, declined in the West Kootenayfrom Shelter Bay to Goldstream River north ofRevelstoke, and near Castlegar, and on ornamentalbirch in Prince George. There were only very smallpopulations in birch trees in Fort St. James that werelightly discolored by birch leaf miner, Bucculatrixcanadensisella, in 1990.

Satin mothLeucoma salicis

Satin moth larvae were less numerous in the southOkanagan, following an increase in 1990, but larvaewere common again in small numbers near Golden.None was seen near Chilliwack following theircollapse in that area in 1990.

Populations of satin moth in cottonwood nearBrookmere in the Okanagan Valley declined

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significantly following severe defoliation over 5 hain 1990, the first recorded infestation in the areasince the mid-1960s. Small numbers of larvae, buttoo few to cause significant defoliation, were againcommon on aspen at a golf course near Golden nearstands previously defoliated by forest tent caterpillar.Increased numbers of adults were common in theNorth Thompson River Valley in the KamloopsRegion in areas near aspen stands defoliated byforest tent caterpillar from Barriere to Avola.

Western winter mothErannis tiliaria vancouverensis

Populations of western winter moth in theVancouver Region generally remained at low levelsfollowing their collapse in 1990, but they defoliatedbroadleaf and vine maples and other deciduous hostsnorth of Spuzzum in the Fraser Canyon. Populationsin the West Kootenay were also at low levels andthere was no apparent defoliation.

Deciduous hosts at Alexandria Bridge ProvincialPark were moderately and severely defoliated overabout 20 ha, which was the only defoliation visiblein the Vancouver Region in 1991. Small numbers oflarvae were common between Hope and Boston Barand near Cultus Lake and Emory Creek provincialparks, but there was no visible defoliation. Anuclear polyhedrosis virus (NPV), historically thecause of population declines, was prevalent at CultusLake Provincial Park in 1989, 1990, and 1991, and atSasquatch Provincial Park in 1989 and 1990.

There was no evidence of populations whichlightly defoliated trembling aspen in the WestKootenay for the first time in 1990 near Fruitvale,from Castlegar to Trail, and on birch near BeaverFalls.

Winter moth and Bruce spanwormOperophtera brumata and 0. bruceata

Winter moth populations declined in the lowermainland following two years of increase, and alsodeclined on southern Vancouver Island following anincrease in 1990, the first in six years. Brucespanworm populations were less common in thelower mainland and the Fraser Valley wherepopulations increased slightly in 1989 and 1990.Larvae were also less common in trembling aspen inthe Peace River area that were defoliated bydeclining populations of forest tent caterpillar,Malacosoma disstria, and large aspen tortrix,Choristoneura conflictana.

Declining winter moth populations this yearcaused very little defoliation of birch stands nearHighway 99 and the New Westminster Highway,and in scattered fruit and other deciduous treesfrom Ladner to Surrey, where defoliation wasmoderate and severe in 1990. Very lightdefoliation occurred at widely scattered areasthroughout Vancouver, White Rock, Richmond,and parts of the upper Fraser Valley which werefirst defoliated last year. On southern VancouverIsland, where defoliation of deciduous trees,mainly Garry oak, has been greatly reduced by theintroduction of parasites, winter moth was commonbut not damaging in a small number of patches,which was similar to 1990.

A native defoliator, Bruce spanworm, was oftenassociated in low numbers with winter moth onbroadleaf and vine maples on the lower mainlandand the Fraser Valley, but defoliation was minimal.Larvae were less common in trembling aspendefoliated by forest tent caterpillar and large aspentortrix in the Peace River area of the Prince GeorgeRegion.

Parasitism of winter moth at six sites byintroduced parasitoids averaged 57% (by Cyzenisalbicans, a parasitic fly), and 10% (by Agryponflaveolatum, a parasitic wasp).

Jumping gall waspNeuroterus saltatorius

Discoloration and premature loss of foliage causedby the gall wasp on Garry oaks in the Victoria areaincreased for a sixth consecutive year. A survey ofpopulations and damage on Garry oaks in the Capitalregional district, in cooperation with localmunicipalities, found a significant expansion of theinfestation. Defoliation was severe and widespreadfrom Cattle Point in Oak Bay to William Head inMetchosin and north to Mount Newton near Sidney.Populations were found in low numbers for the firsttime on Salt Spring and Galiano Islands.

Parasitism of the jumping gall wasp ranged from0 to 30% but was too low to effectively reducepopulations, which are forecast to continue in 1992.

An oak leaf phylloxeranPhylloxera sp. nr. glabra

Defoliation of Garry oak by the phylloxeran rangedfrom 25 to 100% of the foliage on about 10% of thetrees in widely scattered patches throughout theCapital regional district. Foliage discoloration andsubsequent defoliation by the introduced phylloxeran

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(an aphid-like sucking insect) generally occurs onthe same trees each year, which progressivelyreduces tree vigor. Predators of the phylloxeranwere common but too few to effectively reducepopulations.

Apple ermine mothYponomeuta malinella

Defoliation of apple trees was less widespread andless severe in mainland areas of the VancouverRegion in 1991. This decline was predicted in 1990when there were fewer larvae and pupae than inprevious years. Widespread severe defoliation wasfirst recorded in the region in 1989. The cause of thedecline has been attributed to natural factorsincluding climate.

An introduced pest, the ermine moth was firstdetected in British Columbia in 1981 in a nursery onVancouver Island. Larvae have since been detectedon native crabapple and on neglected apple treesthroughout much of the lower mainland, on eastcoastal areas on Vancouver Island, and in the drierparts of the Thompson and Shuswap river valleysfrom Lytton to Little Fort and Malakwa.

Populations are expected to decline further in1992 in most previously infested areas, paticularly inthe Vancouver Region. This prediction is based onthe reduced number of larvae found in 1991.

Pear thripTaeniothrips inconsequens

Pear thrips were found for the first time in BritishColumbia in 1989, and were again found in 1990 onbroadleaf maple near the University of Victoria.Populations were very low and there was nosignificant damage. None was found elsewhereduring surveys of broadleaf and vine maples in theVancouver and Nelson regions in 1990, and nonewas found in 1991.

A diminutive sucking insect, hardly visible tothe naked eye, pear thrips were introduced to NorthAmerica where it was first found in 1904. Theyhave since spread to most of the United States. Pearthrips caused severe defoliation of sugar maple innortheastern states in 1988, and this promptedsurveys across Canada in 1989-90.

Dogwood leaf blightDiscula (= Gloeosporium) destructans

Severe foliar infection and branch dieback of nativeand some planted dogwoods was widespreadthroughout the host range in the Vancouver ForestRegion for the second consecutive year. Wet springweather for at least three years has resulted incumulative mortality of lower branches, and severediscoloration of most of the crown was common.Tree mortality has been limited to single trees atwidespread locations, but mortality has increasedwhere severe infections reoccur.

New Records of Occurrence and Distribution

Twenty new disease collections were recorded in theregion in 1991. Most were relatively minor foliageor bark disorders or saprophytes. Six collectionswere new records within either British Columbia orthe Yukon Territory. An additional 14 diseases wererecorded for the first time on new hosts; eight onconifers and six were found on deciduous trees andshrubs.

One insect collection was a new species, threecollections represented significant extensions of theirknown distributions within the region, and a fourthcollection was a first record in the insectarycollection. A budmoth, Clepsis sp., introduced toNorth America from Europe, was collected in smallnumbers for the first time in British Columbia onwhite spruce in a nursery at Abbotsford. A jumping

gall wasp on Garry oak, Neuroterus saltatorius, wascollected at widespread locations throughout theGreater Victoria area, which is a significantextension of its previously known distribution. Anoak leaf phylloxeran, Phylloxera sp. nr. glabra, wascollected on Salt Spring and Galiano islands, whichis an extension of its previously known distributionat Victoria. Cherry bark tortrix, Enarmonia formosa,was found on cherry at Sidney, which was the firstrecord of the insect outside the Fraser Valley; this isthe only known area in Canada with this introducedtortrix. Yew big bud mite, Cecidophyopsis psilaspis,was collected at Victoria, Port Renfrew, andNanaimo. This was the first collection of this insectfor the Pacific Forestry Centre insectary.

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Forest Insect and Disease Surveyin the Pacific and Yukon Region

Who they are and what they do

The Forest Insect and Disease Survey (FIDS) is anationally coordinated program of six regional FIDSunits and the FIDS Technology DevelopmentProject. The program provides perspectives oninsects and diseases including acid rain to forestmanagers, quarantine agencies, researchers,educators, and the public.

At the Pacific Forestry Centre, there are 18positions within the FIDS organization headed byDr. Allan Van Sickle. From May into October, 11rangers work throughout six forest regions in BritishColumbia and in the Yukon Territory. Their regularreports are based on ground and aerial observations,egg counts, pheromone traps, plantationexaminations, stand cruises, sketch maps, and othersurvey techniques. Most reports are supported bysamples of the damaging agents.

Verification of the damaging agents isperformed by Herbarium and Insectary staff.Collections which contain 26 000 disease specimensrepresenting 3300 organisms and 66 000 insectsrepresenting 6000 different species, and theirassociated records, are essential for the correctidentification of forest pests causing damage in thePacific and Yukon Region.

A geographic information system enablesanalysis and presentation of insect or disease maps,

in combination with major geographic boundaries,bio-geoclimatic zones and forest inventory andclimatic information. This system was expandedduring 1991 to improve its overlay capabilities andallow better links with other users. The system alsolinks to a data retrieval and query system containingmore than half a million insect and disease recordsfrom the region's forests.

Communication of information to operationalforest managers is an important aspect of FIDS. Toalert local managers and the public to new orthreatening outbreaks, "Pest Reports" may be issuedduring the field season. In addition to this regionalreport, more detailed information for each provincialforest region is compiled and distributed.Contributions are also made to national forestrystatistics and to a national report which outlines pestconditions in forests across Canada.

Forest insects and diseases will increasinglyinfluence how forests are managed. Detailedmeasurements of losses for a range of pests andsituations can be combined with survey results toimprove statistics and to guide research and forestmanagement. FIDS in the Pacific and Yukon Regionis an integral part of the team required to solve majorproblems and reduce uncertainty in the complex,long-range management of forest crops.

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